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I am writing a piece of software that needs pre-rendered UV maps for on the fly texture mapping. I tried rendering these maps in blender, but the color values in the resulting image do not change in a linear fashion.

UV map

If you open this image in an image editing program and drag the eyedropper tool horizontally or vertically across the square you will notice that the color values change very rapidly at first then the change slows down.

This results in distorted texture mapping when using a basic shader like this.

gl_FragColor = texture2D(u_source, vec2(uvmap.x, uvmap.y));

Distorted texture

Is there a way to render a UV map with linear color value change in blender?

Community
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Lukas Kriaučiūnas
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    related: http://blender.stackexchange.com/questions/40253/cycles-gradient-texture-node-linear-is-not-linear –  Nov 14 '15 at 09:13

2 Answers2

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Save as EXR. EXR is the only linearized format available.

troy_s
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I managed to fix it by setting the render view to raw and the exposure to 0 in the scene render view options.

Lukas Kriaučiūnas
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  • This is a sub optimal approach. Better is to flag the image as "non color" if using a display referred format such as TIFF, or better, use OpenEXR which is strictly linearized by default. – troy_s Sep 10 '16 at 05:40