title: Lossless document image compression

authors: Inglis, Stuart J.

abstract: Document image compression reduces the storage requirements for digitised books or documents by using characters as the fundamental unit of compression. Compression gains can be achieved by identifying regions that contain text, isolating unique characters, and storing them in a codebook.

This thesis investigates several fundamental areas of the compression process. Algorithms for each area are tested on a corpus of images and the improvements tested for statistical significance. Methods for isolating characters from a bitmap are investigated along with techniques for determining reading order. We introduce the use of the docstrum to aid image compression and show that it improves upon previous methods. The Hough transform is shown to be an accurate method for determining page skew and gives robust results over a range of image resolutions. Compression is shown to improve when the skew of an image is determined automatically, and used to determine reading order.

If images can be segmented into regions of text and non-text, it is possible to change the compression model to reflect the region’s contents. Instead of developing ad hoc methods to classify the regions, we introduce the use of machine learning schemes, and show both high predictive accuracy and compression improvements. Machine learning schemes are also applied to the problem of matching characters to determine similarity. Using the scheme’s choice of parameters, the matching methods and their respective compression gains can be compared fairly. We investigate the changes in codebook size and compression gains when compressing multiple pages.

The compression system presented is complete, free of arbitrarily introduced parameters and achieves the best known lossless compression on a public corpus of images.

text: Lossless document image compression Document image compression reduces the storage requirements for digitised books or documents by using characters as the fundamental unit of compression. Compression gains can be achieved by identifying regions that contain text, isolating unique characters, and storing them in a codebook.

This thesis investigates several fundamental areas of the compression process. Algorithms for each area are tested on a corpus of images and the improvements tested for statistical significance. Methods for isolating characters from a bitmap are investigated along with techniques for determining reading order. We introduce the use of the docstrum to aid image compression and show that it improves upon previous methods. The Hough transform is shown to be an accurate method for determining page skew and gives robust results over a range of image resolutions. Compression is shown to improve when the skew of an image is determined automatically, and used to determine reading order.

If images can be segmented into regions of text and non-text, it is possible to change the compression model to reflect the region’s contents. Instead of developing ad hoc methods to classify the regions, we introduce the use of machine learning schemes, and show both high predictive accuracy and compression improvements. Machine learning schemes are also applied to the problem of matching characters to determine similarity. Using the scheme’s choice of parameters, the matching methods and their respective compression gains can be compared fairly. We investigate the changes in codebook size and compression gains when compressing multiple pages.

The compression system presented is complete, free of arbitrarily introduced parameters and achieves the best known lossless compression on a public corpus of images.

year: 1999

title: Catania's Concept of the Operant Revisited: Empirical Analysis of Response Variation and Controlling Contingencies

authors: Oliver, Gary Kelson

subjects: Operant

abstract: Six Shaver‐Starcross hens with no prior experimental experience served as participants in two experiments which were designed to empirically test Catania's concept of the operant. The stimulus consisted of a cream coloured rectangle against a black background shown on a standard LCD computer monitor. An infrared touch screen mounted to the front of the LCD monitor recorded the location of all responses made by the participants. Experiment one consisted of autoshaping the rectangle pecking response. This was done using an automated computer program designed to eliminate latencies between responses and reinforcement, as well as positional biases which may have been introduced via manual autoshaping. The program successfully eliminated latencies and positional biases introduced by the experimenter, but took longer than anticipated to autoshape the desired response in the participants. It is suggested that procedural differences account for the unusual length of time taken to autoshape the participants in this experiment. Preliminary inquiry investigating procedural differences shows that it may be possible to model speed of acquisition more accurately than done so at present, without retrospective analysis of the acquisition data itself. In experiment two the active, reinforced zone of the rectangle was reduced. The participants had no visible cue demarcating active and inactive zones of the rectangle, yet in accordance with Catania's operant, responding across all participants came to fall within the active, reinforced zone of the rectangle. The results; shifts in response distributions in relation to the changes in contingencies, offer empirical support for Catania's operant in terms of positive reinforcement across a single parameter of responding. The implications of these findings imply that when variability in responding is important; for example in learning, exploring, creating, and problem solving, Catania's operant may be favourable over Skinner's operant as a vehicle for identifying and controlling variables associated with behavioural outcomes due to its greater topographical inclusivity. Contemporary behavioural analysis favours a behavioural systems approach where the respondent and operant class distinction merges; the environment affects the organism as much as the organism affects the environment. Catania's operant is complementary to behavioural analysis in this vein.

text: Catania's Concept of the Operant Revisited: Empirical Analysis of Response Variation and Controlling Contingencies Six Shaver‐Starcross hens with no prior experimental experience served as participants in two experiments which were designed to empirically test Catania's concept of the operant. The stimulus consisted of a cream coloured rectangle against a black background shown on a standard LCD computer monitor. An infrared touch screen mounted to the front of the LCD monitor recorded the location of all responses made by the participants. Experiment one consisted of autoshaping the rectangle pecking response. This was done using an automated computer program designed to eliminate latencies between responses and reinforcement, as well as positional biases which may have been introduced via manual autoshaping. The program successfully eliminated latencies and positional biases introduced by the experimenter, but took longer than anticipated to autoshape the desired response in the participants. It is suggested that procedural differences account for the unusual length of time taken to autoshape the participants in this experiment. Preliminary inquiry investigating procedural differences shows that it may be possible to model speed of acquisition more accurately than done so at present, without retrospective analysis of the acquisition data itself. In experiment two the active, reinforced zone of the rectangle was reduced. The participants had no visible cue demarcating active and inactive zones of the rectangle, yet in accordance with Catania's operant, responding across all participants came to fall within the active, reinforced zone of the rectangle. The results; shifts in response distributions in relation to the changes in contingencies, offer empirical support for Catania's operant in terms of positive reinforcement across a single parameter of responding. The implications of these findings imply that when variability in responding is important; for example in learning, exploring, creating, and problem solving, Catania's operant may be favourable over Skinner's operant as a vehicle for identifying and controlling variables associated with behavioural outcomes due to its greater topographical inclusivity. Contemporary behavioural analysis favours a behavioural systems approach where the respondent and operant class distinction merges; the environment affects the organism as much as the organism affects the environment. Catania's operant is complementary to behavioural analysis in this vein.

year: 2009

title: Racism and Employment: A Narrative Review of Aotearoa New Zealand and International Qualitative Studies

authors: Tan, Kyle K. H.

abstract: In Aotearoa New Zealand, employment inequities exist for minoritised ethnic groups (Māori, Pasifika, Asian, racialised migrants and refugees) in the forms of barriers to employment, occupation inequities, differences in promotion to leadership roles, ethnic pay gaps and discriminatory experiences at workplaces. In this review, we compiled Aotearoa qualitative studies to depict the dynamics of racism alongside other intersectional forms of prejudices that disadvantage the employment processes and career progression of minoritised ethnicities. Literature gaps in Aotearoa research were identified through reviewing international literature published between 2016 and 2021. Reviewed Aotearoa studies were categorised into three themes: unemployment and underemployment, workplace discrimination, and strategies for navigating racism. Drawing upon a framework that recognises racialised processes as spanning across micro- (individual), meso- (organisational) and macro- (institutional) levels, we found most Aotearoa studies analysing racism in the workplace focus on micro-level experiences. Compared with international literature, research in Aotearoa has yet to consider the roles of organisations and technologies as racialised structures that engender employment inequities, and the interaction of individuals in response to meso- and macro-structures that build on settler colonialism and racism. Our review echoes the call of Aotearoa scholars to name racism as the overarching oppressive mechanism embedded within organisations and to use anti-racism praxes such as te Tiriti o Waitangi as a way forward to promote employment equity.

text: Racism and Employment: A Narrative Review of Aotearoa New Zealand and International Qualitative Studies In Aotearoa New Zealand, employment inequities exist for minoritised ethnic groups (Māori, Pasifika, Asian, racialised migrants and refugees) in the forms of barriers to employment, occupation inequities, differences in promotion to leadership roles, ethnic pay gaps and discriminatory experiences at workplaces. In this review, we compiled Aotearoa qualitative studies to depict the dynamics of racism alongside other intersectional forms of prejudices that disadvantage the employment processes and career progression of minoritised ethnicities. Literature gaps in Aotearoa research were identified through reviewing international literature published between 2016 and 2021. Reviewed Aotearoa studies were categorised into three themes: unemployment and underemployment, workplace discrimination, and strategies for navigating racism. Drawing upon a framework that recognises racialised processes as spanning across micro- (individual), meso- (organisational) and macro- (institutional) levels, we found most Aotearoa studies analysing racism in the workplace focus on micro-level experiences. Compared with international literature, research in Aotearoa has yet to consider the roles of organisations and technologies as racialised structures that engender employment inequities, and the interaction of individuals in response to meso- and macro-structures that build on settler colonialism and racism. Our review echoes the call of Aotearoa scholars to name racism as the overarching oppressive mechanism embedded within organisations and to use anti-racism praxes such as te Tiriti o Waitangi as a way forward to promote employment equity.

year: 2024-01-01