Patent Publication Number: US-8985735-B2

Title: Deposition of print treatment

Description:
BACKGROUND 
     Some printing systems form a printed image by ejecting printing fluids from printheads. Thereby, printing fluids, such as treatment fluids and inks, are applied onto a print medium for printing a pattern of individual dots at particular locations. The printed pattern reproduces an image on the printing medium. At least some of these printing systems are commonly referred to as inkjet printers. 
     A treatment fluid may be used for enhancing print quality of a printed pattern. For example, a pre-treatment fluid (e.g., a fixer) may be applied on a substrate location prior to ink deposition for addressing coalescence, bleed, feathering, or similar effects caused by ink or pigment migration across the printed surface. Alternatively, or in addition thereto, a post-treatment fluid (e.g. a coating), may be applied on a substrate location after ink deposition for protecting the printed pattern. 
     Common methods for applying a treatment fluid include roll coating, spray coating, manual application or treatment ejection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the present disclosure may be well understood, various examples will now be described with reference to the following drawings. 
         FIG. 1  is a block diagram schematically illustrating a printing system in which examples can be implemented. 
         FIG. 2  is a block diagram schematically illustrating components for implementing examples. 
         FIG. 3  is a flow chart that implements examples of printer operation control data generation. 
         FIG. 4  is a flow chart that implements examples of image printing. 
         FIG. 5A  schematically shows a substrate according to examples.  FIG. 5B  schematically shows a portion of the substrate in  FIG. 5A . 
         FIG. 6  shows a generation of control data according to examples. 
         FIG. 7  schematically shows details of a treatment deposition unit according to examples. 
         FIGS. 8A and 8B  graphically illustrate treatment deposition according to the flow chart of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of the examples disclosed herein. However, it will be understood that the examples may be practiced without these details. While a limited number of examples have been disclosed, it should be understood that there are numerous modifications and variations therefrom. Similar or equal elements in the Figures may be indicated using the same numeral. 
     An image may be reproduced on a substrate by printing a pattern of individual dots. Inkjet printers print dots by ejecting very small drops of ink onto the print medium via one or more printheads each having ink ejecting nozzles as set forth below with respect to  FIG. 1 . 
     Print quality is one of the most important considerations in printing. Since the image output of an inkjet printer is formed of thousands of individual ink drops, the quality of the image is dependent upon the quality of each ink drop and the arrangement of the ink drops on the print medium. 
     One common problem that may degrade quality of a printed image is ink migration across the substrate onto which it is deposited. This might cause a lack of edge sharpness. In an ideal environment, ink drops would form a perfect circle of uniform size when applied to a medium. However, it is common for ink drops to bleed or feather into surrounding areas when applied to a medium. If the surrounding area is a non-ink area, then the resulting image will not have a well-defined edge. If the surrounding area is another ink drop, then the colors of the two ink drops may combine, producing a different undesirable color. In either case, the quality of the image may be seriously degraded. The printing artifacts may be respectively referred to as bleeding and feathering. 
     Ink migration may cause other artifacts such as coalescence, in which ink droplets on the substrate may merge. Merged ink droplets may form pools and puddles that, when drying, may cause visible non-uniformities. 
     Another common problem that may affect printing is slow drying of ink. For example, after printing of a page is complete, the printer may need to hold a page for letting the ink drying before depositing the page in an output tray. This may place an undesirable limit on how fast consecutive pages can be printed. 
     Another problem that may appear is poor water fastness. After ink dries on a substrate, it might be desirable to maintain the integrity of the image even if a small amount of moisture, such as perspiration from one&#39;s hand, is applied to the image. If the image has poor water fastness, moisture may cause the ink to bleed or run, thereby seriously degrading the printed image. 
     Another problem that may appear once an inked pattern is printed on substrate is susceptibility to scratches or rubbing that may degrade print quality. 
     For addressing the above problems, some approaches have been employed. 
     One approach is to use special inks that will either react with each other or with the medium to improve edge sharpness and ink adherence to the substrate. This approach, however, severely restricts the types of inks that can be used in inkjet printing systems. Another approach is to use special media that promotes fast adherence of inks thereto. This approach may be very restrictive since special media (e.g., specially purchased paper) may be required when printing with a desired print quality. 
     Another approach for addressing the above problems is to use a treatment fluid. For example, via a treatment fluid, fixer may be applied on inked dots. The fixer may prevent ink to spread beyond locations where it is deposited. Fixer deposition for addressing bleeding and/or feathering may include blooming in order to add robustness against printer misalignment. By blooming fixer is also applied to substrate locations surrounding inked dots. Other treatment fluids may be used. For example a coating may be applied on inked dots to address at least some of the above problems or to provide a protecting coating to a printed pattern. 
     Applying treatment to a substrate may, however, cause some undesirable effects. Applying too much treatment to each dot location can cause the medium to warp or cockle. Using too much treatment may also unacceptably increase print costs. On the other hand, using too little treatment may not achieve the desired print quality and, more specifically, negatively affect some printing output parameters such as, chroma, water fastness, strike through avoidance, and edge sharpness. 
     In order to address problems related to treatment application, it has been elsewhere proposed to apply on a substrate location a variable amount of treatment, the treatment amount depending on a quantity of ink to be applied to the substrate location. However, variable treatment application may not be efficient at high ink densities since there deposition of treatment beyond a certain amount may not convey any substantial improvement in print quality. 
     It has also been proposed to apply a constant amount of treatment. However, at low ink densities, the percentage of deposited treatment relative to deposited ink may be too high resulting in deposition of more treatment that actually required. This might result on unnecessary waste of treatment and/or undesired effects due to the relatively high amount of treatment relative to ink. 
     In at least some of the examples herein, printing methods are disclosed that facilitate an efficient deposition of treatment. For substrate locations with a relatively low ink density, a treatment is variably applied in order to avoid an excess of treatment fluid. This might be seen as a variable treatment-to-ink regime. Blooming may be omitted at the relatively low ink densities since, for those ink densities, bleeding and/or feathering may not be perceivable. 
     On the other hand, for substrate locations with a relatively high ink density, an efficient treatment usage may be provided by applying a constant treatment amount (this might be seen as a constant treatment-to-ink regime) and combining it with blooming. A constant treatment amount refers to applying an amount of treatment irrespective of how much the ink amount exceeds the threshold. Blooming, as used herein refers to depositing treatment on dot locations surrounding a dot location identified to receive a certain amount of ink. Blooming may be restricted to substrate dot locations that are not determined to receive ink. Further, printing may be performed such that all substrate dot locations to receive treatment via blooming are to receive the same amount of treatment. In other examples, blooming is not restricted to substrate dot locations that are not determined to receive ink. 
     Such examples combine the benefits of (1), applying treatment variably, i.e., with a treatment amount adapted to the local ink conditions, and (2) constantly applying treatment using blooming for robustness. Further, such examples consider when one of these approaches conveys the most benefits. More specifically, such examples facilitate an efficient usage of treatment by taking into account a threshold that determines when using one of approaches (1) or (2) is more effective. Further, such a treatment application can be implemented in a computational efficient manner. It should be taken into account that due to required print speeds, computational capabilities for determining treatment application may be significantly limited. 
     The following description is broken into sections. The first, labeled “Environment,” describes environments in which examples may be implemented. The second section, labeled “Components,” describes various physical and logical components for implementing various examples. The third section, labeled a “Operation,” describes steps taken to implement various embodiments. 
     Environment:  FIG. 1  is a block diagram of a printer  100 , in which examples can be implemented. It will be understood that the following description of printer  100  is merely illustrative and does not limit the components and functionality of examples described in the present disclosure. 
     As shown in the diagram, printer  100  includes a carriage  102  with a printhead receiving assembly  104 . In the illustrated example, printer  100  is illustrated including printhead  106  in printhead receiving assembly  104 . Carriage  102  is to transition printhead  106  across the width of a substrate  108 , i.e., along printhead transition directions  110 ,  112 . For example a drive  146  may be coupled to carriage  102  for effecting carriage transition. Thereby, printer  100  can perform printing across a width of substrate  108  via translation of carriage  102 . In other examples, printhead  106  is a page-wide array printhead and translation is not required for printing across a width of substrate  108 . 
     Printhead  106  in this example is illustrated to include a plurality of ink printhead units  114 ,  116 ,  118 ,  120 . Each of the ink printhead units is configured to eject ink  122  of a different color via respective ink nozzle array arrangement  124 ,  126 ,  128 ,  130 . Ink printhead units  114 ,  116 ,  118 ,  120  are fluidly connected to an ink reservoir system  132 . Ink reservoir system  132  includes ink reservoirs  132   a ,  132   b ,  132   c ,  132   d  for providing ink to the respective ink printhead units. In the illustrated example, ink reservoirs  132   a ,  132   b ,  132   c ,  132   d  respectively store cyan ink, magenta ink, yellow ink, and black ink. 
     Base colors may be reproduced on substrate  108  by depositing a drop of one of the above mentioned inks onto a substrate location. Further, secondary colors can be reproduced by combining ink from different ink printhead units. In particular, secondary or shaded colors can be reproduced by depositing drops of different base colors on adjacent dot locations in the substrate location (the human eye interprets the color mixing as the secondary color or shading). It will be understood that further ink reservoirs may be provided. For example, a CcMmKY system may include further ink reservoirs for light cyan (c) and light magenta (m). 
     According to some examples herein, printer  100  may include at least one printhead unit for ejecting a pre-treatment fluid  146   a  and/or at least one printhead unit for ejecting a post-treatment fluid  146   b . In the example of  FIG. 1 , treatment printhead units  134 ,  136  are for treating a substrate location (e.g., any of substrate dot locations  504  depicted in  FIG. 5B ). Treatment printhead unit  134  is for applying a pre-treatment  146   a  (e.g., a fixer) on the substrate location via a pre-treatment nozzle arrangement  138 . More specifically, in at least some examples herein, a treatment fluid to be deposited is a fixer. A fixer fluid may be configured as described in U.S. Pat. Nos. 4,694,302, 5,746,818, or 6,132,021, which are incorporated by reference. 
     Treatment printhead unit  134  is for applying a post-treatment  146   b  (e.g., a coating) on the substrate location via a post-treatment nozzle arrangement  142 . A post-treatment may be as described by U.S. patent application Ser. No. 12/383,066 published under publication number US 2012/0120142. 
     The block diagram in  FIG. 1  shows treatment printhead units  134 ,  136  fluidly connected to, respectively, a pre-treatment fluid reservoir  140   a  and a post-treatment fluid reservoir  140   b . Treatment fluid reservoirs  140   a ,  140   b  are to store the treatment fluid to be jetted by treatment nozzles  138 ,  142 . For example, pre-treatment fluid reservoir  140   a  may store a printing fluid including an ink fixer component; post-treatment fluid reservoir  140   b  may store a printing fluid including a coating component. Ink reservoir system  132  and treatment fluid reservoirs  140   a ,  140   h  may include disposable cartridges (not shown). The reservoirs may be mounted on carriage  102  in a position adjacent to the respective printhead. In other configurations (also referred to as off-axis systems), the reservoirs are not mounted on carriage  102  and a small fluid supply (ink or treatment) is externally provided to the printhead units in carriage  102 ; main supplies for ink and fixer are then stored in the respective reservoirs. In an off-axis system, flexible conduits are used to convey the fluid from the off-axis main supplies to the corresponding printhead cartridge. Printheads and reservoirs may be combined into single units, which are commonly referred to as “pens”. 
     It will be appreciated that examples can be realized with any number of printhead units depending on the design of the particular printing system, each printhead unit including a nozzle array for jetting a printing fluid such as ink or treatment. For example, printer  100  may include at least one treatment printhead unit, such as two or more treatment printhead units. Furthermore, printer  100  may include at least one ink printhead unit, such as two to six ink printhead units, or even more ink printhead units. 
     In the illustrated examples, ink printhead units are located at one side of a treatment printhead. It will be understood that ink printheads may be located at both sides of a treatment printhead. Further, printhead units might be monolithically integrated in printhead  106 . Alternatively, each printhead unit might be modularly implemented in printhead  106  so that each printhead unit can be individually replaced. Further, printhead  106  may be a disposable printer element or a fixed printer element designed to last for the whole operating life of printer  100 . 
     Printer  100  further includes a controller  148 , which is operatively connected to the above described elements of printer  100 . Controller  148  is shown configured to execute a print job received from a printout source  150  according to control data  105 . Via control data  105  it might be determined whether, for one or more substrate location, how treatment fluid is to be ejected, e.g. whether according to a variable treatment-to-ink regime or to a constant treatment-to-ink regime. Control data  105  may be generated based on data for print job source  150 . Further, control data  105  may be generated by print job source  150  and provided to controller  148 . Controller  148  is shown to include processor  154 . Processor  154  is configured to execute methods as described herein. In some examples, printer  100  includes an application-specific integrated circuit (ASIC) configured to generate control data  105  as illustrated by examples herein. 
     Processor  154  may be implemented, for example, by one or more discrete modules (or data processing components) that are not limited to any particular hardware, firmware, or software (i.e., machine readable instructions) configuration. Processor  154  may be implemented in any computing or data processing environment, including in digital electronic circuitry, e.g., an application-specific integrated circuit, such as a digital signal processor (DSP) or in computer hardware, firmware, device driver, or software (i.e., machine readable instructions). In some implementations, the functionalities of the modules are combined into a single data processing component. In other versions, the respective functionalities of each of one or more of the modules are performed by a respective set of multiple data processing components. 
     Memory device  152  is accessible by controller  148  and, more specifically, by processor  154 . Memory device  152  may be integrated within controller  148  or may be a separate component communicatively connected to controller  148 . Memory device  152  stores process instructions (e.g., machine-readable code, such as computer software) for implementing methods executed by controller  148  and, more specifically, by processor  154 . 
     Program instructions in memory device  152  may be part of an installation package that can be executed by processor  154  to implement control engine  108 . In this case, memory  152  may be a portable medium such as a CD, DVD, or flash drive or a memory maintained by a server from which the installation package can be downloaded and installed. In another example, the program instructions may be part of an application or applications already installed. Here, memory  152  can include integrated memory such as a hard drive. It should be noted that a tangible medium as used herein is considered not to consist of a propagating signal. In examples, the medium is a non-transitory medium. 
     Controller  148  receives print job commands and data from print job source  150 , which may be a computer or any other source of print jobs, in order to print an image based on a print mask. The received data may include treatment control data  105 . A print mask refers to logic that includes control data determining which nozzles of the different printheads are fired at a given time to eject fluid in order to reproduce a print job. The print mask may be processed according to control data  105  by processor  154  in order to cause ejection of treatment according to examples herein. In an example, control data  105  forms part of a print mask supplied by print job source  150 . Alternatively, control data  105  might be implemented in the print mask by a pre-processing performed by processor  154 , or any other processor, so that treatment is ejected as disclosed herein. 
     Controller  148  is operatively connected to treatment printhead units  134 ,  136 , ink printhead units  114 ,  116 ,  118 ,  120 , and the respective reservoirs to control, according to the print mask and the control data in memory  152 . Thereby, controller  148 , and more specifically processor  154 , can control functionality of printer  100  such as, but not limited to printing according to control data  105 . 
     It will be understood that the functionality of memory  152  and print job source  150  might be combined in a single element or distributed in multiple elements. Further, memory  152  and print job source  150  may be provided as external elements of print system  100 . Further, it will be understood that operation of processor  154  to control treatment ejection is not limited to the above examples. 
     Components: At least some of the functionality described herein can be implemented as components comprised of a combination of hardware and programming configured for performing tasks described herein (for example, blocks in the flow charts illustrated below with respect to  FIGS. 3 and 4 ). 
       FIG. 2  depicts examples of physical and logical components for implementing examples illustrated herein. In illustrating  FIG. 2 , reference is made to printer  100  in  FIG. 1 . It will be understood that this reference is merely illustrative and does not limit components of examples herein. 
     In the example of  FIG. 2 , the programming may be processor executable instructions stored on a tangible memory media, e.g., memory  152  and the hardware may include processor  154  for executing those instructions. Memory  152  can be said to store program instructions that when executed by processor  154  implements, at least partially, controller  148  shown in  FIG. 1 . Memory  152  may be integrated in the same device as processor  154  or it may be separate but accessible to that device and processor  154 . Memory  152  and processor  154  may be respectively comprised of single, integrated components or may be distributed over a number of discrete memory units and processor units. Such discrete memory units and processor units may be included in the same integrated component (e.g., controller  148 ) or may be distributed over different, communicatively connected, components (e.g., a controller comprised of multiple discrete components). 
     Program instructions in memory  152  may be part of an installation package that can be executed by processor  154  to implement examples herein. In this case, memory  152  may be a portable medium such as a CD, DVD, or flash drive or a memory maintained by a server from which the installation package can be downloaded and installed. In another example, the program instructions may be part of an application or applications already installed. Here, memory  152  can include integrated memory such as a hard drive. It should be noted that a tangible medium as used herein is considered not to consist of a propagating signal. In examples, the medium is a non-transitory medium. 
     In  FIG. 2  the executable program instructions stored in memory  152  are depicted as a treatment determination module  202  and a treatment application module  204 . It will be understood that these modules may be combined or configured differently as shown in  FIG. 2  for realizing examples herein. 
     Treatment determination module  202  is configured to determine how treatment fluid is to be deposited. Treatment determination module  202  may be configured to process treatment ejection data that specifies operation of a treatment printhead. For example, treatment determination module  202  may merely process treatment control data  105  (illustrated above with respect to  FIG. 1 ). Alternatively, or in addition thereto, treatment determination module  202  is configured to generate treatment control data  105  based on image data (example image data  602  is shown in  FIG. 6 ). Generation of control data is illustrated below with respect to  FIG. 3 . 
     For generating control data  105 , module  202  may access look-up tables  208 , stored in data store  206 . Look-up tables  208  may be designed to transform image data (e.g., RGB data  602   a - 602   c  shown in  FIG. 6  below) into printer control data  105 . Printer control data  105  may be comprised of color plane(s)  210 , which determines in which substrate dot locations ink is to be deposited, and treatment plane(s)  212 , which determines in which substrate dot location treatment is to be deposited. Color plane(s)  210  and treatment plane(s)  212  may be also stored in data store  206 . Data store  206  represents, generally, any memory capable of storing data that can be accessed by form fill device in the performance of its functions. Generation of color and treatment planes is illustrated below with regard to  FIG. 6 . 
     Treatment application module  204  is configured to cause a printer, e.g., printer  100  in  FIG. 1 , to apply treatment as described herein. For example, module  204  may receive treatment control data  105  from treatment determination module  202  and cause printer  100  to apply the treatment in individual substrate dot locations accordingly. Treatment application is illustrated below with respect to  FIG. 4 . 
     Operations:  FIGS. 3 and 4  show flow charts illustrating examples. In discussing  FIGS. 3 and 4 , reference is made to  FIGS. 1 and 2  to provide contextual examples. Implementation, however, is not limited to those examples. Reference is also made to the example forms depicted in  FIGS. 5 to 8B . Again, such references are made simply to provide contextual examples. 
       FIG. 3  shows a flow chart  300  that implements examples of methods for generating printer operation control data (e.g., control data  105  shown in  FIG. 5 ). Blocks in flow chart  300  may be executed by controller  148 , shown in  FIG. 1 . In an example, blocks in flow chart  300  are implemented by treatment determination module  202  illustrated above with respect to  FIG. 2 . 
     At block  302 , an image to be printed is processed. The processing at block  302  may include receiving image data  602  to be printed by printer  100 . The image data may be provided by a computing system externally connected to printer  100  via a physical connection (e.g., a USB cable or the like), or a wireless connection (via a wireless local area network). Image data may be comprised of a set of rot, green, blue (ROB) values for each pixel on the image (e.g., image data  602  shown in  FIG. 6 ). At block  302 , RCB values associated with a specific substrate dot location may be identified from image data  602  and made available for the ink amount determination at block  304 . 
     In the present description, a substrate dot location is understood as an area of a substrate onto which a pixel of an image is to be reproduced.  FIG. 5A  illustrates a substrate  500  on which printer  100  may print an image. Substrate  500  can be a sheet of paper, a transparency, or any other medium which is suitable for printing, such as a textile or a banner substrate. A small section  502  of substrate  500  is indicated in  FIG. 5A . 
       FIG. 5B  shows a close up view of section  502  of substrate  500 . Section  502  is comprised of substrate dot locations  504  locations where ink and/or treatment may be applied to reproduce the image. In general, the number and size of substrate dot locations  504  are not limited. For example, in certain applications, there might be 300 dot locations per inch in both the vertical and horizontal direction of substrate  500 . In such an example, the spacing between each dot location  504  may be 1/300 of an inch. In other examples, there may be 600 or 1200 dot locations per inch. The spacing between the dot locations in such examples may be 1/600 of an inch and 1/1200 of an inch, respectively. 
     Referring back to  FIG. 3 , at block  304 , from the image processed at block  302 , an amount of ink to be deposited at a first dot location  504  on substrate  500 . First dot location  504  may be any of the substrate dot locations shown in  FIG. 5B . Block  302  may involve a color conversion from image data to the color space of the printer. In other words, pixel data of the image may be translated to the color gamut of the printer to be used. For example, image data  602  shown in  FIG. 6  may be converted to CMYK values  604   a - 604   d  corresponding to the color space of printer  100 . From the CMYK values, ink amounts to be deposited on single dot locations can be derived. It will be understood that this derivation may include some processes such as printer channel linearization and/or halftoning. 
     At block  306 , the ink amount determined at block  304  is compared to a threshold to determine a treatment-to-ink regime. 
     In examples herein, the threshold is an ink amount limit that may be pre-determined based on one or more factors. Generally the threshold is pre-determined as the ink amount limit above which depositing a constant treatment amount and blooming is sufficient to satisfy certain print quality requirements. In such examples, below the pre-determined ink amount limit blooming may not provide any significant advantage and a proportional deposition of amount of ink facilitates an efficient usage of treatment. 
     In general, a trial-and-error approach may be used to determine a threshold that is suitable for a required print quality requirement. For example, the threshold may be determined via experimentation by printing test patches using different ink amounts. The printed test patches may be a sequence that starts with a low ink amount and successively increases ink amounts. For printing the test patches, variable and constant treatment-to-ink regimes may be interleaved. Thereby, it might be assessed ink amounts for which print quality is satisfactory or not for different treatment-to-ink regimes. 
     Alternatively, or in addition thereto, the above procedure may be performed varying print parameters (e.g., used inks, substrates, or printing conditions such as temperature or humidity). Thereby, a threshold may be determined specific to certain print parameters such as printing conditions, used inks, or used substrates. It will be understood that a value of the threshold may be pre-determined in a number of manners. 
     In an example, if the treatment fluid includes a fixer, above the pre-determined threshold (for example, an ink amount limit between 1 and 4 drop-per-pixels, dpp, such as 2 dpp), applying a constant fixer amount is determined to be sufficient for controlling ink migration; further, below the pre-determined threshold, applying bleeding is determined not to convey a significant advantage since the low ink amount to be deposited does not cause a significant bleeding effect; further, below the pre-determined threshold, applying a variable fixer (e.g., a fixer amount proportional to ink to be deposited) is determined to be a more efficient usage of treatment. 
     Referring back to  FIG. 3 , at block  306  it is assessed whether the ink amount is below a threshold. It will be understood that other equivalent comparisons are feasible. For example, it might be assessed whether the ink amount is greater than the threshold. Process flow  300  may be then accordingly adapted. 
     In the example illustrated in  FIG. 3 , if at block  306  it is assessed that the ink amount is below the threshold, then process flow  300  goes to blocks  308  and  310 , where printer operation control data  105  for applying treatment according to a variable treatment-to-ink regime is generated. A variable treatment-to-ink regime refers to generating control data in which treatment to be deposited on the substrate dot location is selected to be dependent on the ink amount. For example, the treatment to be deposited in the substrate dot location may be selected to be proportional to the ink amount, as illustrated below with respect to  FIGS. 8A and 8B . Further examples on variable treatment application are illustrated in U.S. patent application entitled “Print”, by Marc Rossinyol Casals et al, with application Ser. No. 13/229,186, filed on Sep. 9, 2011 and assigned to the present assignee. 
     If at block  306  it is assessed that the ink amount is not below the threshold, then process flow  300  goes to blocks  312  and  310  where printer operation control data  105  for applying treatment according to a constant treatment-to-ink regime is generated. A constant treatment-to-ink regime includes applying bloom in dot locations surrounding the first dot location. 
     In a constant treatment-to-ink regime, a selected constant treatment amount is deposited. In other words, for any amount of ink exceeding the threshold, the same treatment amount is deposited on the substrate dot location. The selected constant treatment amount to be deposited when the ink amount is above a threshold is, generally, a treatment amount that is sufficient to address issues caused by ink mobility. In an example, the selected constant treatment amount is a maximal treatment amount. The maximal treatment amount may be determined by the capacity of printer  100  to deposit treatment during a pass over the substrate location for printing on a single dot. Printer  100  may be designed so that maximal treatment amount is a certain percentage of the maximal amount of ink that can be deposited on a single substrate location, e.g. a percentage between 5 and 15% of the maximal ink amount such as 8%. 
     There are a variety of options for applying blooming. Some examples on how blooming may be applied are illustrated in, for example, U.S. Pat. No. 6,598,965, which is incorporated herein by reference in its entirety (to the extent in which this document is not inconsistent with the present disclosure) and in particular those parts thereof describing blooming. In some example, in the constant treatment-to-ink regime, the same treatment amount is to be applied to the first dot location and to dot locations surrounding the first dot location used at block  304  onto which blooming is applied. 
     Process flow  300  illustrates treatment deposition onto a single substrate dot location. It will be understood that process flow  300  may be extended for generating control data for all substrate dot locations that are to be printed for reproducing a complete image. Thereby, complete sets of data might be generated that determines where and how treatment is to be applied. Printer  100  may address these data sets to apply treatment for reproducing a complete image on a substrate. 
     It will be understood that there are a variety of options for generating printer operation control data. Some examples for generating control data for applying treatment on a substrate are illustrated in, for example, U.S. Pat. No. 6,598,965, which is incorporated herein by reference in its entirety (to the extent in which this document is not inconsistent with the present disclosure) and in particular those parts thereof describing circuits for treatment data generation. 
     Control data generation may imply generating one or more treatment planes indicating printing system  100  where to apply treatment. Such examples of control data generation are illustrated in the following with respect to  FIG. 6 .  FIG. 6  illustrates generation of control data  105  for operating printer  100  to deposit treatment fluid. In the example illustrated in  FIG. 6 , control data  105  also includes data for operating printer  100  to deposit inks. 
     The basis for control data generation is image data  602 . Image data  602  is comprised of a plurality of pixels, each pixel having associated thereto a RGB value. Therefore, image data  602  can be seen as being comprised of three color planes: a red (R) plane  602   a , a green (G) plane  602   b , and a blue (B) plane  602   c . Image data  602  may be color converted to generate color planes corresponding to the color gamut of printer  100 . For example, a color conversion  606  may be used to transform the RGB planes  602   a - 602   c  into CMYK planes  604   a - 604   d . Each CMYK plane may be comprised of ink amount values to be applied on substrate dot locations for reproducing the image associated to image data  602 . If the printer includes further ink channels (e.g., a light cyan and/or a light magenta channel), further corresponding planes may be generated. 
     There are a variety of options for storing ink amount values in CMYK planes  604   a - 604   d . For example, ink amount values may be stored as 8 bit values associated to specific substrate dot locations. These ink amount values can then be used as input values for printhead units  114 ,  116 ,  118 ,  120  when positioned over the corresponding substrate dot locations. 
     Color conversion  606  is configured depending on the specific requirements of the particular printing systems. For example, color conversion  606  may be comprised of look-up tables (e.g., look-up tables  208  shown in  FIG. 2 ) addressing image data  602  for generating CMYK planes  604   a - 604   d . Such look-up tables may, additionally to color conversion, perform further conversion operations such as, but not limited to, linearization and halftoning. 
     Ink amounts to be deposited on substrate dot locations can be derived from CMYK planes  604   a - 604   d  and used to build one or more treatment planes for determining where and under which treatment-to-ink regime a treatment printhead unit (e.g., any of treatment printhead units  134  and  136  shown in  FIG. 1 ) is to deposit treatment. In examples, treatment planes may be built for accomplishing each treatment-to-ink regime. Each of the treatment planes may be associated to different deposition units. For example, a treatment plane may be built comprising data for causing a treatment deposition unit to deposit treatment according to the variable or constant treatment-to-ink regime. Another treatment plane may be built comprising data for causing deposition of treatment in bloomed locations. 
     These deposition units refer to treatment deposition units that are separately addressable for deposition of treatment. For example, as illustrated by  FIG. 7  one or both of printhead units  134  and  136  of printer  100  may include a first trench  702  to deposit treatment according to a first treatment plane and a second trench of  704  to deposit treatment according to a second treatment plane. First trench  702  is comprised of a first set  706  of nozzles  708 . Second trench  704  is comprised of a second set  710  of nozzles  708 . It will be understood that the deposition units may be implemented differently. For example, deposition units may be implemented by separate printhead units that independently addressable. 
     Referring back to  FIG. 6 , a first treatment plane T 1  is built via an ink-to-treatment transform  608  that addresses data from CMYK planes  604   a - 604   d . In an example, ink-to-treatment transform  608  is such that first treatment plane T 1  contains data for causing a deposition unit to deposit treatment according to the variable treatment-to-ink regime or to the constant treatment-to-ink regime. For example, first treatment plane T 1  may be built via transform  608  to cause (1) treatment deposition proportional to the local amount of ink in substrate dots with an ink amount below a threshold, and (2) constant treatment deposition in substrate dots with an ink amount above the threshold. 
     In an example, if the ink amount associated via CMYK planes  604   a - 604   d  to a substrate dot location is below a threshold (e.g., 2 dpp), the treatment in a corresponding location in plane T 1  is set to be proportional to the ink amount. If the ink amount associated via. CMYK planes  604   a - 604   d  to a substrate dot location exceeds the threshold, the treatment in a corresponding location in plane T 1  is set to a maximum value possible. Then halftoning may be performed at the threshold value, so that T 1  is comprised of (1) areas with low half-toned values (e.g. 0 or 1), where ink is low and treatment is to be applied proportional to ink, and (2) areas with high half-toned values (e.g. 3), where ink is above the threshold, and treatment is to be applied under a constant treatment-to-ink regime. T 1  may be then processed using a special mask (e.g., using a LUT), so that the half-toned values are printed. 
     The resulting plane T 1  may be addressed by a further transform  610  for generating a second treatment plane T 2  for causing a second treatment deposition unit to deposit treatment in bloomed locations surrounding locations associated with the constant treatment-to-ink regime. Transform  610  may populate second treatment plane T 2  for blooming areas in first treatment plane T 1  that correspond to a constant treatment-to-ink regime. 
     Each of the resulting planes T 1  and T 2  are then to be printed with a different trench  702  or  704  in treatment print units  134 ,  136 . Thereby, a computationally efficient generation of treatment can be implemented via the generation of multiple treatment planes. It will be understood that there are other options for generation the treatment deposition data. For example, a single treatment plane can be built by combining each of the resulting planes T 1  and T 2 . Such a single treatment plane can then be used to operate a single treatment deposition unit implementing both treatment-to-ink regimes. 
     In the following, treatment deposition is illustrated with respect to  FIG. 4 .  FIG. 4  shows a flow chart  400  that implements examples of methods for printing on substrate dot locations  504 . Blocks in flow chart  400  may be executed by controller  148 , shown in  FIG. 1 . In an example, blocks in flow chart  400  are implemented by treatment application module  204  illustrated above with respect to  FIG. 2 . 
     At block  402 , control operation data  105  is processed. For example, data generated via process flow  300  may be accessed and made readily available to controller  148  for operation of one or more of treatment printhead units  134 ,  136  in  FIG. 1 . Control operation data  105  may include data for operating ink printhead units, e.g., one or more of printhead units  114 ,  116 ,  118 ,  120  in  FIG. 1 . 
     As represented by block  404 , the manner on which treatment application is applied depends on whether an ink amount to be applied on a substrate dot location  504  is above or below the threshold mentioned above. 
     If the ink amount to be deposited in a substrate dot location is below a threshold, the selected treatment-to-ink regime includes depositing at block  406  an amount of treatment in that substrate dot location. In the specific example of  FIG. 4 , for low ink amounts, the treatment amount is proportional to the ink amount. As set forth above, other treatment-to-ink dependencies are foreseen for low ink amounts (e.g., an exponential treatment-to-ink dependency). 
     If the ink amount to be deposited in a substrate dot location is above the threshold, the selected treatment-to-ink regime includes depositing at block  408  a selected constant amount of treatment in the substrate dot location. Further, block  407  also includes blooming in an area surrounding the specific substrate dot location. 
     Treatment deposition according to flow chart  400  is graphically illustrated in  FIGS. 8A and 8B . Graph  800  shows percentage of treatment (relative to ink amount) against ink amount (in drop-per-pixel units, dpp) to be deposited on substrate dot locations to receive ink. Graph  802  shows amount of treatment (in drop-per-pixel units, dpp) against ink amount (in drop-per-pixel units, dpp) to be deposited on a specific substrate dot location. In this example, a threshold  804  is set at 2 dpp. The threshold defines a variable treatment-to-ink regime  806  and a constant treatment-to-ink regime  808 . 
     In this example, as shown in graph  800 ,  802 , at variable treatment-to-ink regime  806 , the amount of treatment to be deposited for low ink amounts (i.e., below threshold  804  at 2 dpp) is proportional to the ink amount. In the example, this proportionality is set to a fixed percentage of 12%. Such a variable treatment-to-ink regime facilitates that an efficient treatment is performed while preventing that too much treatment is applied at very low ink amounts. 
     Further, at constant treatment-to-ink regime  806 , the amount of treatment to be deposited for high ink amounts (i.e., above threshold  804  at 2 dpp) is constant. Such a variable treatment-to-ink regime facilitates that an efficient treatment is performed for high ink amounts since, there, higher treatment might not provide substantial improvements in print quality, in particular in view of application of blooming to surrounding substrate dot locations. Further, it can be understood from  FIG. 8A  that if the constant treatment-to-ink regime would be extended to low ink amounts this would result in a high treatment amount relative to applied ink, which might negatively impact print quality due to treatment overflow. 
     Conclusion: In at least some of the examples above, techniques related to print treatment deposition are illustrated. 
     It will be appreciated that examples above can be realized in the form of hardware, programming or a combination of hardware and the software engine. Any such software engine, includes machine-readable instructions, may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage substrate are embodiments of a tangible computer-readable storage medium that are suitable for storing a program or programs that, when executed, for example by a processor, implement embodiments. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a tangible or intangible computer readable storage medium storing such a program. A tangible computer-readable storage medium is a tangible article of manufacture that stores data. (It is noted that a transient electric or electromagnetic signal does not fit within the former definition of a tangible computer-readable storage medium.) 
     In the foregoing description, numerous details are set forth to provide an understanding of the examples disclosed herein. However, it will be understood that the examples may be practiced without these details. While a limited number of examples have been disclosed, numerous modifications and variations therefrom are contemplated. It is intended that the appended claims cover such modifications and variations. Further, flow charts herein illustrate specific block orders; however, it will be understood that the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be scrambled relative to the order shown. Also, two or more blocks shown in succession may be executed concurrently or with partial concurrence. Further, claims reciting “a” or “an” with respect to a particular element contemplate incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Further, at least the terms “include” and “comprise” are used as open-ended transitions.