Draw Guide

Chapter 6,
Editing Images
Raster Graphics

CopyrightThis document is Copyright © 2021 by the LibreOffice Documentation Team. Contributors arelisted below. This document maybe distributed and/or modified under the terms of either the GNU
General Public License (https://www.gnu.org/licenses/gpl.html), version 3 or later, or the Creative
Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), version 4.0 or later.
All trademarks within this guide belong to their legitimate owners.

Contributors
To this editionPeter SchofieldElzett Kotze

Jean Hollis Weber

Martin Fox
Peter Schofield

Jean Hollis Weber
Regina Henschel

To previous editions
John Cleland
John A Smith
Claire Wood

Feedback
Please direct any comments or suggestions about this document to the Documentation Team’s
mailing list: documentation@global.libreoffice.org

Note
Everything sent to a mailing list, including email addresses and any other personal
information that is written in the message, is publicly archived and cannot be deleted.

Publication date and software version
Published July 2021. Based on LibreOffice 7.1 Community. Other versions of LibreOffice may
differ in appearance and functionality.

Using LibreOffice on macOS
Some keystrokes and menu items are different on macOS from those used in Windows andLinux. The table below gives some common substitutions for the instructions in this document.
For a detailed list, see the application Help.
Windows or LinuxmacOS equivalent

EffectTools > Options

LibreOffice > Preferences

Access setup options

Right-click

Control+click or right-click
depending on computer setup

Open a context menu

Ctrl (Control)⌘ (Command)

Used with other keys

F11

⌘+T

Open the Styles deck in the Sidebar

Documentation for LibreOffice is available at https://documentation.libreoffice.org/en/Contents
Copyright............................................................................................................................2
Contributors.............................................................................................................................. 2
Feedback.................................................................................................................................. 2
Publication date and software version.......................................................................................2
Using LibreOffice on macOS.....................................................................................................2

Introduction........................................................................................................................4
Importing images...............................................................................................................4
Inserting.................................................................................................................................... 4
Embedding................................................................................................................................ 5
Linking...................................................................................................................................... 6
Editing links............................................................................................................................... 6
Scanning................................................................................................................................... 7
Copying and pasting................................................................................................................. 8
Dragging and dropping.............................................................................................................. 8

Exporting graphics............................................................................................................8
Exporting files........................................................................................................................... 8
Exporting objects...................................................................................................................... 9

Formatting images (raster objects).................................................................................9
Naming images....................................................................................................................... 10
Image toolbar.......................................................................................................................... 10

Cropping images.............................................................................................................13
Quick cropping........................................................................................................................ 13
Crop dialog.............................................................................................................................. 14
Exporting cropped graphics.....................................................................................................15
Compressing images.............................................................................................................. 15

Image filters......................................................................................................................16
Replacing colors..............................................................................................................22
Color Replacer dialog.............................................................................................................. 22
Replacing colors..................................................................................................................... 23
Replacing transparent areas...................................................................................................24

Conversion.......................................................................................................................24
Contour conversion................................................................................................................. 24
Polygon conversion................................................................................................................. 25
Conversion options and controls........................................................................................25
Converting.......................................................................................................................... 25
Breaking............................................................................................................................. 26
Splitting.............................................................................................................................. 27
Bitmap conversion................................................................................................................... 27

Chapter 6, Editing Pictures | 3

Introduction
Earlier chapters of this Draw Guide have dealt only with vector graphics. The most common
types of vector graphics in use are as follows:•

SVG (Scalable Vector Graphics) – an Extensible Markup Language (XML) based vector
image format for two-dimensional graphics with support for interactivity and animation.

•

EPS (Encapsulated PostScript) – a PostScript document format usable as a graphics fileformat. EPS files are more-or-less self-contained, reasonably predictable PostScript
documents that describe an image or drawing and can be placed within another
PostScript document.

•

AI (Adobe Illustrator) – a proprietary file format developed by Adobe Systems forrepresenting single-page vector-based drawings in either the EPS or PDF formats.

However, Draw also contains a number of functions for handling raster graphics (bitmaps) suchas photographs and scanned pictures, including import, export, and conversion from one format
to another.
Draw can read all the majority of graphic file formats. It has a subset of capabilities similar toraster graphics programs like Adobe Photoshop or Gimp. Raster graphics are generally images
or pictures that use one of the following formats, which are the most common formats in use:•

JPG/JPEG – acronym for Joint Photographic Experts Group which created the format. It
is the most common image format on websites and most digital cameras produce JPEG
images as default.

•

GIF (Graphics Interchange Format) – GIF is a bitmap image format that is popular
because of its wide support and portability.

•

PNG (Portable Network Graphics) – PNG is a raster image format which supports
lossless data compression and also background transparency.

•

TIF/TIFF (Tagged Image File Format) – TIFF is flexible, adaptable, and capable of storing
image data in a lossless format.

•

BMP (BitMaP) – it is also known as bitmap image file, which is a dot matrix data
structure.

Importing images
Inserting
To import image files into a drawing, go to Insert > Image on the Menu bar or click on Insert
Image on the Standard toolbar to open the Insert Image dialog (Figure 1).
Draw contains import filters for the majority of graphic formats. If the file being imported has agraphic format not covered by the import filters, then it is recommended to use one of the many
free graphic conversion programs to convert the file into a format that Draw recognizes.
If Preview is selected in the Insert Image dialog, a preview of the file is shown in the box on theright-hand side. This makes it easier to select the file required and also checks that Draw canimport the file format used.

4| Chapter 6, Editing Pictures

Figure 1: Insert Image dialog

Embedding
Embedding a graphic into a drawing makes the image a permanent part of the drawing. Anychanges made to an embedded graphic only appear in the drawing where the graphic wasembedded. The original graphic file is not affected.
Embedding happens when a graphic is imported into a drawing using one of the following
methods:•

Insert Image dialog.

•

Copying and pasting.

•

Scanning a graphic.

•

Dragging and dropping between open files.

The main advantage of embedding graphics into a drawing is that the graphic is always available
no matter what computer is used to open the drawing.
The main disadvantage of embedding graphics is that it creates large file sizes, which may not bedesirable if there is limited capacity for storing computer files. Also, if the original graphic is
altered, then the embedded graphic is not updated each time the drawing is opened.

Note
When a graphic is to be embedded into a LibreOffice drawing, make sure that theInsert as Link option is not selected in the Insert Image dialog.

Chapter 6, Editing Pictures | 5

Figure 2: Confirm Linked Graphic dialog

Linking
Linking to the original graphic does not insert the graphic into a drawing, but creates a link towhere the original graphic file is located on the computer. Each time the drawing is opened, anylinked graphics are displayed in the drawing.
The main advantage of linking a graphic file when placed in a drawing is that if the originalgraphic file is altered or replaced with a graphic using the same filename, the version of thegraphic in the drawing is always up to date. The next time the drawing is opened, the latest
version of the graphic is also opened in the drawing. Also the file size of the drawing is muchsmaller and the original graphic can easily be edited with specialized external applications.
The main disadvantage of linking graphics is that the link must be maintained between thedrawing and the embedded graphic file for linking to work correctly. If the drawing or originalgraphic file is moved to another computer location, then any links must be updated to include the
new location.
1) Open the Insert Image dialog.
2) Select the Insert as Link option in the Insert Image dialog.
3) Select the required graphic file and click on Open to open the Confirm Linked Graphic
dialog (Figure 2).
4) Click on Keep Link to link the file and close the Confirm Linked Graphic dialog.
5) If necessary, click on Embed Graphic to embed the file if it is not to be linked. This also
closes the Confirm Linked Graphic dialog.

Note
When a graphic file is linked to a LibreOffice drawing, the format of the linked graphic
is not changed.

Editing links
Links can be updated, modified, or broken as follows:
1) Go to Edit > Links to External File on the Menu bar to open the Edit Links dialog(Figure 3).
2) Select the link to be edited.

6| Chapter 6, Editing Pictures

Figure 3: Edit Links dialog
3) Click on Modify, Break Link, or Update as appropriate.
– Modify – changes the graphic file in the drawing to the graphic file that uses theselected link.
– Break Link – breaks the link between the selected file and the current document. The
version of the graphic file in the drawing becomes embedded into the drawing. A
confirmation dialog opens asking if the link is to be broken. Click on Yes to confirm thebreaking of the link.
– Update – updates the selected link so that the most recent version of the linked file isdisplayed in the drawing.
4) Click on Close to save the changes to the link and close the Edit Links dialog.

Scanning
With most scanners a scanned image can be inserted into a drawing or document. Scanned
images are embedded using PNG format. Make sure the scanner is configured for the computerand supported by the SANE system for a Linux operating system, or TWAIN for a Windows or
Mac operating system.
1) Place a document, drawing, or photograph in the scanner and make sure that the scanneris switched on and ready.
2) If this is the first time the scanner has been used with LibreOffice, go to Insert > Media >Scan > Select Source on the Menu bar to select the scanner. If the scanner has beenused before, go to Insert > Image > Scan > Request on the Menu bar.
3) The rest of the procedure depends on the scanner driver, interface, and computer
operating system. Normally, scanning options need to be specified such as resolution,scan window, and so on. Consult the documentation that came with the scanner for more
information.

Chapter 6, Editing Pictures | 74) When the image has been scanned, Draw places it in the drawing. At this point it can beedited like any other graphic.

Note
If more than one scanning device is connected to the computer, the device isselected when the source is selected. This selection becomes the default source
when using scan requests until another device is used as the scanning source.

Copying and pasting
Copying and pasting a graphic into a drawing is another way of embedding graphics. The copiedgraphic can be an image already embedded in another document or drawing, or it can be agraphic file such as a drawing, document, or photograph.
After copying, select the format for pasting a graphic into Draw using Edit > Paste Special >Paste Special on the Menu bar to open the Paste Special dialog. Available formats for pasting
depend on the type of image copied onto the clipboard.

Note
When copying and pasting images into a drawing, please respect the copyright andlicense of the image being copied.

Dragging and dropping
Dragging and dropping is another method of embedding graphics into a drawing and can be usedon graphics that have been embedded or linked. The way that dragging and dropping works isdetermined by the computer operating system. Behavior of dragging and dropping is normallycontrolled using the Ctrl or Ctrl+Shift keys in combination with the mouse.
Objects and images which are used frequently can be stored in the Draw Gallery. From theGallery, a copy of the object or image can be simply dragged onto the drawing. Working with theGallery is dealt with in Chapter 11, Advanced Draw Techniques.

Exporting graphics
Exporting files
By default Draw saves drawings in the *.ODG format. Some software programs cannot open*.ODG files. To make drawings available for other programs, the file can be exported in various
formats. The export procedure used depends on the computer setup and computer operating
system being used. The following procedure is an example export procedure.
1) Open the ODG file being exported.
2) Go to File > Export on the Menu bar and open the Export dialog. An example of anexport dialog is shown in Figure 4.
3) Enter a new filename for the exported file and navigate to the folder where the exported
file is to be saved.
4) Select the required file format from the options in the drop-down list.
5) Click Export and the file is exported as a new file in the selected file format.

8| Chapter 6, Editing Pictures

Figure 4: Example export dialog
6) Depending on the file format selected, another dialog may open allowing options to be
selected for the export format.
7) Depending on the additional dialog that may open, click on Export, Create, or OK and
the file is exported as a new file in its new format.

Exporting objects
Exporting individual objects, or a group of objects, from a drawing file is similar to “Exporting files”
above. Open a drawing file and then select the object or objects for export. Make sure to choose
the Selection option in the export dialog, as shown in Figure 4.
Using this method, an imported image can be modified, annotations added to it, and make otherchanges, then select it and export for use in another drawing or document.

Formatting images (raster objects)
Images (raster graphics) can be edited and formatted using one of the following methods to add
or change filters and adjust the properties of color, lines, areas, and shadows:•

Go to Format > Image on the Menu bar and use one of the tools in the sub-menu that
opens.

•

Use the tools on the Image toolbar. See “Image toolbar” on below for more information.

Chapter 6, Editing Pictures | 9

•Use the tools available in the Shadow and Image sections on the Properties deck of the
Sidebar (Figure 6 on page 12).

•

Some raster graphics may have a text element. For more information on formatting text,
see Chapter 9, Adding and Formatting Text.

Raster graphics included in a group behave like other objects when the properties of the groupare edited and formatted.

Note
Any formatting changes made to a graphic using the tools in LibreOffice only appear
in the drawing where the graphic was modified. The original graphic file is notaffected.

Naming images
Draw names objects, including inserted images, Shape 1, Shape 2, and so on, in the order of
insertion into a drawing. It is recommended to rename objects, including images in a drawing,with a unique name Names make images and other objects easily identifiable in the LibreOffice
Navigator.
1) Select an image, then use one of the following methods to open the Name dialog, wherea unique name can be entered for the selected image:– Go to Format > Name on the Menu bar.
– Right-click on the image and select Name from the context menu.
2) Enter a name in the Name box and click OK.

Image toolbar
The Image toolbar (Figure 5) normally appears when an image or picture that is a raster graphic
is selected. The Image toolbar can be fixed at the top of a drawing or as a floating toolbar. The
default set of tools on the Image toolbar are as follows. For more information on the Image
toolbar and the available tools, see Appendix B, Toolbars.
•

Position and Size (F4) – opens the Position and Size dialog. See Chapter 3, Working
with Objects for more information.

•

Align Objects – opens a sub-toolbar giving access to alignment tools for aligningselected objects in relation to each other. See Chapter 5, Combining Multiple Objects formore information.

•

Bring to Front (Shift+Ctrl++) – brings the selected object to the front of a group of
objects.

•

Bring Forward (Ctrl++) – brings the selected object forward one step.

•

Send Backward (Ctrl+–) – sends the selected object one step backward.

•

Send to Back (Shift+Ctrl+–) – sends the selected object to the back of a group of objects.

•

In Front of Object – moves the selected object in front of another selected object.

•

Behind Object – moves the selected object behind another selected object.

•

Reverse – reverses the order of the selected objects. This tool is grayed out if only one
object is selected.

10| Chapter 6, Editing Pictures

Figure 5: Image toolbar•

Line Style – opens a drop-down list with different line styles used for the outline of theborder. See Chapter 4, Changing Object Attributes for more information.

•Line Width – used to change the width of a line. See Chapter 4, Changing Object
Attributes for more information.

•Line Color – used to change the color of a line. See Chapter 4, Changing Object
Attributes for more information.

•

Area Style/Filling – used to change the type of filling used in a shape. See Chapter 4,
Changing Object Attributes for more information.

•

Shadow – sets the default shadow effect around the picture. The shadow attributes areadjusted using the Shadow section in the Properties deck on the Sidebar (Figure 6). See
Chapter 4, Changing Object Attributes for more information.

•

Filter – opens the Image Filter toolbar which is described in “Image filters” on page 16.

•

Image Mode – changes the display of the graphic from color to grayscale, black andwhite, or a watermark. This setting affects only the display and printing of the picture; theoriginal picture file remains unchanged. The image mode setting can also be changed
using Color mode in the Image section in the Properties deck on the Sidebar (Figure 6).
––––

Default – the graphic is displayed unaltered in color.
Grayscale – the graphic is displayed in 256 shades of gray.
Black/White – the graphic is displayed in black and white.
Watermark – the color, brightness, contrast, and gamma settings are reduced so thatthe graphic can be used as a watermark (background). These default settings can be
adjusted using the Color toolbar (Figure 7).

•

Crop – crops or trims a picture. When using this tool, crop marks appear around thepicture. Drag one or more of these marks to crop the picture to the desired size. For
more information on cropping, see “Cropping images” on page 13.

•

Vertically – flips the selected object vertically. See Chapter 4, Changing Object Attributes
for more information.

•

Horizontally – flips the selected object horizontally. See Chapter 4, Changing Object
Attributes for more information.

•

Transformations – opens the Transformations toolbar. See Chapter 4, Changing Object
Attributes for more information.

•

Transparency – adjusts the degree of transparency of the picture between 0% (opaque)and 100% (fully transparent). The transparency setting can also be adjusted using theImage section in the Properties deck on the Sidebar.

Chapter 6, Editing Pictures | 11

Figure 6: Shadow and Image sections in
Properties deck on Sidebar

Figure 7: Color toolbar

12| Chapter 6, Editing Pictures

•Color – opens the Color toolbar (Figure 7) to adjust the values of the RGB colors,brightness, contrast, and Gamma. These adjustments do not affect the original picture,
but the values are stored in Draw as a separate formatting set. The color settings canalso be adjusted using the Image section in the Properties deck on the Sidebar.
– Red, Green, Blue – select values between –100% (no color) to +100% (full intensity);
0% represents the original color value of the graphic.
– Brightness – select a value between –100% (totally black) and +100% (totally white).
– Contrast – select a value between –100% (minimum) and +100% (maximum).
– Gamma – this affects the brightness of the middle color tones. Select a value between
0.10 (minimum) to 10 (maximum) Try adjusting this value if changing brightness orcontrast does not give the required result.

Cropping images
Cropping is a method of hiding unwanted areas of an image or changing the size of an image ina drawing. Changes made when cropping an image only change the display of the graphic in a
drawing and not the original graphic file.

Quick cropping
After selecting a graphic, it can be cropped quickly using one of the following methods:•

Click on Crop Image on the Standard or Image toolbar.

•

Go to Format > Image > Crop on the Menu bar.

•

Right-click on the image and select Crop from the context menu.

Selection handles appear around the selected image (Figure 8) and the image is cropped asfollows:•

Top, bottom, left, and right selection handles crop the image in one direction only.

Figure 8: Example image ready for cropping with selection
handles

Chapter 6, Editing Pictures | 13•Corner selection handles crop the image vertically and horizontally in two directions.

•

To maintain the ratio between vertical and horizontal dimensions, hold down the Shift key
while moving a selection handle.

Crop dialog
For more control and accuracy over the cropping functions, it is recommended to use the Cropdialog (Figure 9). After selecting an image, go to Format > Image > Crop Dialog on the Menu
bar to open the Crop dialog.
•

Crop – use this section to trim or scale the selected graphic, or to add white spacearound the graphic.
– Keep scale – maintains the original scale of the graphic when cropping so that only
the size of the graphic changes.
– Keep image size – maintains the original size of the graphic when you crop so that
only the scale of the graphic changes. To reduce the scale of the graphic, select thisoption and enter negative values in the cropping boxes. To increase the scale of thegraphic, enter positive values in the cropping boxes.

Figure 9: Crop dialog

14| Chapter 6, Editing Pictures

– Left and Right – if Keep scale is selected, enter a positive amount to trim the left or
right edge of the graphic, or a negative amount to add white space to the left or rightof the graphic. If Keep image size is selected, enter a positive amount to increase thehorizontal scale of the graphic, or a negative amount to decrease the horizontal scaleof the graphic.
– Top and Bottom – if Keep scale is selected, enter a positive amount to trim the top or
bottom of the graphic, or a negative amount to add white space above or below thegraphic. If Keep image size is selected, enter a positive amount to increase thevertical scale of the graphic, or a negative amount to decrease the vertical scale of thegraphic.
•

Scale – this section is used to change the scale of the selected graphic as it appears in a
drawing.
– Width – enter a percentage value to change the width of a selected graphic.
– Height – enter a percentage value to change the height of a selected graphic.

•

Image Size – this section is used to change the size of the selected graphic.
– Width – enter a value for the width of the selected graphic.
– Height – enter a value for the height of the selected graphic.

•

Original Size – the original size of the graphic is displayed above the option. Clicking on
this option and then clicking OK resets the selected graphic to its original size.

Note
In the Crop dialog, the Width and Height are treated as independent values.
Changing one without the other can result in significant distortion of the image andthis may not be what is required.

Exporting cropped graphics
If a cropped graphic is to be used in another drawing, use one of the following methods after
selecting the cropped graphic:•

Go to File > Export on the Menu bar to open the Export dialog. Navigate to thedestination folder, then enter a filename, choose the Selection option, and click on
Export. See “Exporting graphics” on page 8 for more information.

•

Go to Format > Image > Save on the Menu bar or right click on the cropped graphic andselect Save from the context menu. Click on Yes to save the modified image and open
an Image Export dialog. Select the file format required, navigate to the destination folder,then enter a filename and click on Save.

Compressing images
If a large image is inserted into a drawing and resized to fit into the layout of the drawing, thecomplete full-size original image is stored in the drawing file. This preserves its content, possibly
resulting in a large file to store or send by mail.
If some loss of image quality can be accepted, the image can be compressed reducing its data
volume while preserving its display in the page layout;
1) Open the Compress Image dialog (Figure 10) using one of the following methods:– Right-click on the image and select Compress from the context menu.
– Go to Format > Image > Compress on the Menu bar.

Chapter 6, Editing Pictures | 15

Figure 10: Compress Image dialog
2) Select the type of compression and the resolution required.
3) Click on Calculate New Size to update the image information when the Compression
and Resolution settings are changed.
4) When satisfied with the new settings, click OK to apply the settings.
5) If the resulting image is not acceptable, use the keyboard shortcut Ctrl+Z to undo thechanges and select another compression setting.

Image filters
Draw offers eleven filter effects that work on a selected graphic and they can be combined.
Filters always apply to the entire graphic and it is not possible to use filters to edit only a part of
the graphic.
1) Select a raster graphic to open the Image toolbar.
2) Apply an image filter using one of the following methods:– Click on Filter to open the Image Filter toolbar (Figure 11), then select an image filter
to apply.
– Go to Format > Image > Filter on the Menu bar and select an image filter from thecontext menu.

Note
If a graphic is embedded into a drawing, any image filters are applied directly to aselected graphic and the original graphic file is not changed. Save the drawing toretain any filter effects applied to the graphic in a drawing.

16| Chapter 6, Editing Pictures

Figure 11: Image Filter toolbar and available
filters

Note
After a drawing is saved and closed, the effects of image filters become permanent.
If image filter effects are not satisfactory, use Edit > Undo on the Menu bar to cancel
the filter effects before saving the drawing.
The image filters available for application to a raster graphic are as follows:•

Invert – inverts or reverses the color values of a color image (similar to a color negative),or the brightness values of a grayscale image. Apply the filter again to revert to theoriginal graphic (Figure 12).

Figure 12: Invert image filter•

Smooth – softens or blurs the image by applying a low pass filter. This reduces thecontrast between neighboring pixels and produces a lack of sharpness making the image
appear smoother (Figure 13). The effect of the smooth filter can be very subtle. However,the following example shows the Smooth image filter applied at a Smooth radius settingof 50 making the image smooth, but blurred.
Selecting this filter opens the Smooth dialog (Figure 14) where the smooth radiusparameter is set.
Chapter 6, Editing Pictures | 17

Figure 13: Smooth image filter

Figure 14: Smooth dialog•

Sharpen – sharpens the image by applying a high pass filter, adjusting the contrast
between neighboring pixels. The effect increases if the filter is applied several times
making the colors appear faded, as shown by the example in Figure 15.

Figure 15: Sharpen image filter

Figure 16: Remove Noise image filter

18| Chapter 6, Editing Pictures

•

Remove Noise – removes noise by applying a median filter comparing every pixel with
its neighbor. It then replaces any pixel with extreme values that deviate in color by a large
amount from the mean value with a pixel that has a mean color value. The amount ofpicture information does not increase each time the filter is applied. However, there arefewer contrast changes resulting in an image that looks smoother and the effect is very
subtle (Figure 16).

•

Solarization – solarization refers to an effect that looks like what can happen when there
is too much light during photo development and the colors have become partly inverted.
Dark areas appear light or light areas appear dark. In the digital world of photography,
solarization creates a change or reversal of color (Figure 17), similar to the effect of the
Invert image filter.
Selecting Solarization opens the Solarization dialog (Figure 18), where the degree ofsolarization (Threshold value) can be specified. Entering a value above 70% reverses theinversion effect on colors. Selecting Invert reverses the effect of the Solarization image
filter.

Figure 17: Solarization image filter

Figure 18: Solarization dialog•

Aging – aging creates a look that resembles photographs developed in the early days ofphotography (Figure 19). All pixels are set to their gray values and then the green andblue color channels are reduced by the amount specified in Aging degree in the Aging
dialog. Red color channel is not changed.
Selecting the Aging filter opens the Aging dialog (Figure 20), where the Aging degree canbe defined and create an old look for the image.

Chapter 6, Editing Pictures | 19

Figure 19: Aging image filter

Figure 20: Aging dialog•

Posterize – posterizing reduces the number of colors in an image. For example, aphotograph will probably look like a painting when the number of colors is reduced(Figure 21).
Selecting Posterize opens the Posterize dialog (Figure 22), where the number of poster
colors can be defined to produce the effect required.

Figure 21: Posterize image filter

Figure 22: Posterize dialog

20| Chapter 6, Editing Pictures

•

Pop Art – changes the colors of an image converting it to a pop-art format (Figure 23).

Figure 23: Pop Art image filter•

Charcoal Sketch – displays an image as a charcoal sketch. The contours of the image
are drawn in black and the original colors are suppressed (Figure 24).

Figure 24: Charcoal Sketch image filter•

Relief – calculates the edges of an image in relief as if the image is illuminated by a lightsource (Figure 25). Selecting Relief opens the Emboss dialog (Figure 26) where theposition of the Light source is selected producing shadows that differ in direction andmagnitude.

Figure 25: Relief image filter

Figure 26: Emboss dialog

Chapter 6, Editing Pictures | 21

•Mosaic – this image filter joins groups of pixels and converts them into rectangles of asingle color creating an image that appears to be a mosaic (Figure 27). The larger theindividual rectangles created, the fewer details in the mosaic graphic.
Selecting this image filter opens the Mosaic dialog (Figure 28), where the number ofpixels for Width and Height of the tiles is set. Selecting Enhanced edges enhances theedges of each tile, creating a sharper definition.

Figure 27: Mosaic image filter

Figure 28: Mosaic dialog

Replacing colors
The Color Replacer tool only allows replacement or changing a color in an embedded graphic
for another color or set a color as transparent. Up to four colors can be replaced at once. An areaof the graphic cannot be selected for editing as this tool only works on the entire graphic.
The selection of replacement colors can only be from one of the available palettes in LibreOffice.
New colors cannot be defined here, but custom colors can be created before using the Color
Replacer tool. For more information on creating colors, see Chapter 11, Advanced Draw
Techniques.

Note
The Color Replacer can only be used on embedded graphics. If the Color Replacer
is used on a linked graphic, the following error message appears “This image islinked to a document. Do you want to unlink the image in order to edit it?”. Click on
Yes to unlink and embed the graphic.

Color Replacer dialog•

Pipette – switches color selection on when selected.

•

Replace – replaces the selected source colors in the selected image with the colors
specified in the Replace with boxes.

22| Chapter 6, Editing Pictures

•Colors – lists the source colors and the replacement colors.
– Source color checkbox – select this checkbox to replace the current Source color withthe color that specified in the Replace with box.
– Tolerance – set the tolerance for replacing a source color in the source image. To
replace colors that are similar to the color selected, enter a low value. To replace awider range of colors, enter a higher value.
– Replace with – lists the available color palettes and replacement colors.

•

Transparency – replaces transparent areas in the selected image with the color
selected.

Replacing colors
1) Select an embedded image to start using the Color Replacer.
2) Go to Tools > Color Replacer on the Menu bar to open the Color Replacer dialog(Figure 29).
3) Click on Pipette at the top of the Color Replacer dialog to activate the color selectionmode.
4) Move the cursor over the color to be replaced in the selected image and a preview of thecolor appears in the box next to Pipette.
5) Click on the color. The selected color appears in the first Source color preview box and acheck mark appears next to it6) To select another color, place a check mark next to the second Source color preview box
and click on another color in the selected image. A maximum of four colors can beselected in the Color Replacer dialog.
7) Enter the amount of tolerance required for replacing each selected color in the Toleranceboxes. The default selection is 10% tolerance.
8) In Replace with, select a color palette from the drop-down list, then select the required
color from the color palette. Transparent is the default selection.
9) After selecting up to four colors for replacement, click Replace to replace the colors in theselected graphic. An example of color replacement is shown in Figure 30.
10) There is no preview of the effect. If the result is not satisfactory, select Edit > Undo >Color Replacer in the Menu bar and repeat the color replacement.

Figure 29: Color Replacer dialog

Chapter 6, Editing Pictures | 23

Figure 30: Example of using color
replacer

Note
Using the Color Replacer replaces all occurrences of the Source color that are in theselected image.

Note
The default selection of Transparent in the Replace with boxes removes the selectedcolor from the image and creates transparent areas in the selected image.

Replacing transparent areas
To replace any transparent areas in an image with a color use the following procedure:
1) Go to Tools > Color Replacer on the Menu bar to open the Color Replacer dialog.
2) Click on the image with transparent areas to select the image.
3) Select Transparency in the Color Replacer dialog so that a check mark appears next toTransparency.
4) Select a color palette from the drop-down list next to Transparency, then select a color
from the selected palette.
5) Click on Replace and the transparent areas are filled with the selected color.
6) There is no preview of the effect. If the result is not what you required, select Edit > Undo
> Color Replacer in the Menu bar.

Conversion
Contour conversion
Contour conversion converts a selected object to a polygon, or a group of polygons, with four
corner points. If an image was converted to a contour, then the converted image is set as a
background graphic. If the conversion creates a group of polygons (for example, contour
conversion of a text object), then enter the polygon group before selecting an individual polygon
within the group. For more information on working with groups, see Chapter 5, Combining
Multiple Objects.
After an object is converted to a contour, the object can no longer be edited normally. Instead, thecontour converted object is edited using Edit > Points on the Menu bar to adjust its shape. For
more information on editing points, see Chapter 3, Working with Objects.

24| Chapter 6, Editing Pictures

Note
Any editing to an object must be completed before carrying out a contour conversion
because any further editing is not possible on the converted object.
1) Carry out all necessary editing on the object before converting to a contour.
2) Make sure the object is selected.
3) Convert the object to a contour using one of the following methods:– Go to Shape > Convert > To Contour on the Menu bar.
– Right-click on the selected object and select Convert > To Contour from the context
menu.

Note
No confirmation dialog is provided for a contour conversion.

Polygon conversion
Polygon conversion is used to convert a selected image into a group of polygons filled with color.
The image is also converted to a vector graphic and can be resized with no loss of image quality
or distortion of any text.
After conversion, the graphic can be broken into groups of polygons and then split into individual
polygons. Breaking and splitting allows editing or deletion of individual colors within the graphic.

Conversion options and controls•

Number of colors – enter the number of colors to be displayed in the converted image.
LibreOffice generates a polygon for each occurrence of a color in the image. The range
for the number of colors is between 8 and 32.

•

Point reduction – removes color polygons that are smaller than the pixel value entered.
The range for point reduction is between 0 and 32 pixels.

•

Fill holes – fills the blank areas in the graphic that can be created when applying a point
reduction.

•

Tile size – enter the size of the rectangle for the background fill. The range of tile sizes is
between 8 and 128 pixels.

•

Source image – preview of the original image.

•

Vectorized image – preview of the converted image.

•Preview – creates a preview of the converted image in Vectorized image without
applying any changes.

•

OK – converts the image to a vector graphic consisting of polygons. The result is ametafile in SVM format (StarView Metafile) used by LibreOffice and allows transfer of theconverted image to other LibreOffice documents.

Converting
1) Select an image in a drawing.

Chapter 6, Editing Pictures | 25

Figure 31: Convert to Polygon dialog
2) Convert the image into a polygon using one of the following methods and open theConvert to Polygon dialog (Figure 31):
– Go to Shape > Convert > To Polygon on the Menu bar.
– Right-click on the image and select Convert > To Polygon from the context menu.
3) Select Number of colors and Point reduction to be used in the conversion.
4) Select Fill holes to prevent any blank areas appearing in the converted image.
5) Enter the number of pixels to use for Tile size.
6) Click Preview to check how the converted graphic will look.
7) Make any necessary changes to the settings and check the preview again.
8) If the converted image meets the expected requirements, click OK to convert the image toa polygon and close the Convert to Polygon dialog.

Note
No confirmation dialog is provided for a polygon conversion.

Breaking
After converting an image to polygons, the vectorized image can be broken into groups ofpolygons. Each group of polygons consists of one color and becomes an object that can be usedin another drawing.
1) Convert an image to polygons, see “Converting” above.
2) Make sure the converted image is selected, then use one of the following methods tobreak the image into groups of polygons:– Go to Shape > Break on the Menu bar.
26| Chapter 6, Editing Pictures

– Right-click on the image and select Break from the context menu.
3) Click on a color in the image and drag the group of polygons filled with that color out of
the image to create a new image.
4) Alternatively, press Delete and delete the color from the image.

SplittingAfter converting an image to polygons and breaking the image into groups of polygons, thesepolygon groups can be split into individual polygons.
1) Convert an image to polygons, see “Converting” above.
2) Break the image into groups of polygons, see “Breaking” above.
3) Select the image, then use one of the following methods to split the groups of polygons
into individual polygons:– Go to Shape > Split on the Menu bar.
– Right-click on the image and select Shapes > Split from the context menu.
– Use the keyboard shortcut Ctrl+Alt+Shift+K.
4) Select an individual polygon (or several polygons) in the image and drag the polygon fromthe image to create a new image in the drawing.
5) Alternatively, press Delete to delete the selected polygon(s) from the image.

Bitmap conversion
All drawing objects placed into a LibreOffice drawing are vector graphics and these vector
graphics can be converted to a bitmap (raster graphic) in PNG format. Any transparency effects
in the original vector graphic are lost during conversion even though the PNG format used by
LibreOffice Draw supports transparencies.
Use one of the following methods to convert a vector graphic to a bitmap:•

Go to Shape > Convert > To Bitmap on the Menu bar.

•

Right-click on the graphic and select Convert > To Bitmap from the context menu.

Note
No confirmation dialog is provided for a bitmap conversion.

Chapter 6, Editing Pictures | 27