Color blind filters - Inside...
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Transcript of Color blind filters - Inside...
COLOR BLIND FILTERS By Stacey Osborn
OUTLINE
• INTRODUCTION
•PREVIOUS WORK
•DESCRIPTION
•EXPERIMENTS
•RESULTS
•DISCUSSION
INTRODUCTION
Color Blindness or Color Deficiency affects approximately 8% of men and 0.5% of women of European descent. It can be broken down in to three main categories: Monochromacy, Dichromacy and Anomalous Trichromacy. Dichromacy can be further broken down in to Protanopia, Deuteranopia, and Tritanopia.
In this project I focused primarily on the Deuteranopia form of Dichromacy.
INTRODUCTION – CONTINUED
The purpose of this project was to manipulate digital images using several different processing techniques including: a Daltonization Method, a Recoloring Method, A Contrast Adjustment Method, and a LAB Contrast Adjustment Method in order to make them viewable and distinguishable to those with color vision deficiency and determine which method produces the clearest result.
PREVIOUS WORK
• Daltonization – Daltonize.org
• Chrome Daltonize Plugin
• Colorblind Glasses / Contacts
• Smartphone Real Time Filter Applications
• Image Recoloring Techniques
• Contrast Adjustments
• Color Blind Simulators for Developers
• Color Blind Friendly Colormaps for Developers
DESCRIPTION - DALTONIZATION
• The Daltonization method is currently the
most accepted image manipulation
algorithm and has many variations and
improvements and is used in several browser plugins.For this project I used the very simple
version from daltonize.org
• The first step is to find the LMS values of the RGB image using a conversion matrix
• Then another conversion is made to delete the information associated
with the loss of any of the cone types
• Finally the activity is converted back to the RGB color space
DESCRIPTION - RECOLORING
• Recoloring builds on the Daltonization approach requiring more complex algorithms which have been the focus of several recent academic studies • Mass Spring Method
• Rasche Method • Generalized Histogram
Equalization
DESCRIPTION – RECOLORING CONTINUED
•All recoloring methods have the same main goals – Preserving Contrast and Maintaining Luminance
• The Mass Spring Method used in my survey uses three steps: • Image Quantization • Mass Spring Optimization • Reconstruction
DESCRIPTION – RECOLORING CONTINUED
• The Mass Spring Method represents the color gamut of each class of Dichromacy with two half- planes in the LMS color space approximated together to from a single plane passing through the luminance axis
• The luminance axis is determined by mapping the color gamut of each class of Dichromacy to the approximately perceptually-uniform LAB color space and taking the least-squares to obtain a plain that contains the luminance axis
DESCRIPTION – RECOLORING CONTINUED
• Quantization is completed by assigning each quantized color Pi with mass mi and the position of Pi is initialized with the value of the color as seen by a Dichromat after the rotation of the luminance plane
• Each pair of particles is connected with a spring S with an elasticity coefficient k and rest length (quantized length). At each optimization step the positions are updated and the Spring and length are recalculated with the goal that the perceptual distance between all pairs and the quantized color distance will be approximately the same
• The transformed colors are then determined by inversing the rotation of the luminance plane
DESCRIPTION – RECOLORING CONTINUED
• To adjust for the local minima problem, they switch the sign of the b* coordinate of all rotated quantized colors whose a* coordinates are positive with a perceptual distances between the color itself and the color as perceived by a dichromat is greater than a certain threshold in order to: • Avoid ambiguity
• Switching the b* coordinate for some colors compresses and stretches their associated spring adding additional potential energy
DESCRIPTION - CONTRAST
• First the algorithm adjusts an image’s RGB values to enhance contrast between red and green • The pixel values are then cut in half to make room for pixel values to be increased • Then for every pixel:
• Reds and Greens further from pure red or green are increased significantly while those closer are only marginally increased
• For pixels that are mostly red, the blue value is reduced
• For pixels mostly green, the blue value is increased
DESCRIPTION – LAB COLOR CORRECTION
• Similar to the RGB Contrast but performed in the LAB color space, first the image is converted from the RGB color space to the LAB color space
• The a* values are adjusted relative to their maxima making positive numbers more positive and negative numbers more negative
• The b* value is adjusted based on how red or green it is to bring out blue and yellow hues
• The l* value is then adjusted relative to the a* to adjust the brightness
• Finally the image is converted back to the RGB color space
EXPERIMENTS
I created an online survey using Survey Monkey to compare the Daltonization Method, a Recoloring Method, A Contrast Adjustment Method, and a LAB Contrast Adjustment Method. I used 6 image categories with 5 images each and ran the results through the Vischeck program to simulate a Deuteranope color deficiency.
https://www.surveymonkey.com/s/9FJJM8D
EXPERIMENTS – ART Daltonization
Recoloring
Contrast
LAB Contrast
EXPERIMENTS – TEST
Daltonization
Recoloring
Contrast
LAB Contrast
Contrast
EXPERIMENTS - FLOWERS
Daltonization
Recoloring
LAB Contrast
Contrast
EXPERIMENTS - LANDSCAPES Daltonization
Recoloring
LAB Contrast
Contrast
EXPERIMENTS – PEOPLE
Daltonization
Recoloring
LAB Contrast
Contrast
EXPERIMENTS – MAPS / CHARTS
Daltonization
Recoloring
LAB Contrast
Contrast
RESULTS
Daltonization MS Recoloring LAB Contrast Contrast
Art 69 98 51 47
Color Blind Test 29 90 31 115
Flowers 39 176 31 19
Landscapes 84 110 28 43
People 52 148 31 34
Maps and Charts 90 108 45 22
363 730 217 280
Survey was completed online using Survey Monkey with 53 respondents; the Mass Spring
Recoloring method was preferred by a large margin over the other approaches examined.
DISCUSSION
Why Does this Matter to Future Developers?
QUESTIONS ?