2023-04-25 02:12:55 +00:00
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### Copyright
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Copyright (C) 2023 Allen Webster <https://mr4th.com>
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Distributed with GPL 3 license (full license in LICENSE-GPL-3.txt)
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### Contact
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allenw@mr4th.com
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### Purpose
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This is a standalone Win32 OpenGL application that works as a set of
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experiments to demonstrate the behavior and effect of SRGB conversions
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and antialiasing techniques
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In the final output program, the left side shows the gamma-naive results
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where no SRGB conversions are applied to input colors or to output colors.
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The right side shows the gamma-aware results where input colors are converted
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from SRGB to Linear RGB, and output colors are converted from Linear RGB to
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SRGB.
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From top to bottom the experiments are:
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1. A gradient which goes white (1,1,1) to black (0,0,0)
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interpolated linearly by
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alpha = (x - left)/(right - left)
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color = (1,1,1)*(1 - alpha) + (0,0,0)*(alpha)
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2023-04-29 03:00:33 +00:00
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2. Pulls out three colors into solid color blocks:
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(0,0,0), (0.5,0.5,0.5), and (1,1,1)
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3. Tests sRGB -> Linear approximation function. (Right side only)
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Compares two discrete gray pallets.
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The top shows 16 levels of gray by sampling them from an SRGB texture.
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The bottom shows the same 16 gray values with the input colors converted
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from sRGB -> Linear by x^2.2 instead of by texture sampling.
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4. Tests color gradients
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(1,0,0) >>> (1,1,0)
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(1,1,0) >>> (0,1,0)
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(0,1,0) >>> (0,1,1)
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(0,1,1) >>> (0,0,1)
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(0,0,1) >>> (1,0,1)
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(1,0,1) >>> (1,0,0)
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5. Tests partial transparency
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3 horizontal stripes - opaque
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3 vertical stripes - alpha = 0.5
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3 vertical stripes - alpha = 0.75
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6. Tests rectangle anti-aliasing by drawing rectangles with a width
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of 2 placed at various sub-pixel positions
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7. Tests circle anti-aliasing by drawing three circles of various
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radii. The circle anti-aliasing is computed with a highly accurate
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area-under-the-curve integration method - see the "sanity test"
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functions for how the accuracy of the pixel coverage is verified.
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8. Tests circle anti-aliasing with colored backgrounds and shape colors
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to see if anti-aliasing gives rise to any colored fringes.
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In the top-left corner there is a gamma calibration test image. The
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top left corner is "0.5 Gray" in the "Linear color space" and the
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bottom right corner is "0.5 Gray" in the "sRGB color space". The other
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two corners are identical black-and-white checkerboards. When squinting
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to physically blur the checkerboard, the brihgtness should resemble the
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brightness of the top left corner on a correctly calibrated monitor.
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The anti-aliasing of the rectangles and circles should also look better
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on linear color space side for a correctly calibrated monitor.
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