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Brightness & Contrast for Textures

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Hello, We want to display a gray scale texture. Each pixel=8bits. We must have a capability to change the contrast and brightness of the texture. The reason for this is that the user has a monitor with no adjustment. We succeeded doing it with loading a specified color palette and then loading the texture. For this we need the extension: GL_EXT_paletted_texture. Is there an alternative ? Thanks, Zvika Vered

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void glPixelTransferf(
GLenum pname,
GLfloat param
);

void glPixelTransferi(
GLenum pname,
GLint param
);

Pname Type Initial Value Valid Range
GL_MAP_COLOR Boolean false true/false
GL_MAP_STENCIL Boolean false true/false
GL_INDEX_SHIFT integer 0 ( – ,)
GL_INDEX_OFFSET integer 0 ( – ,)
GL_RED_SCALE float 1.0 ( – ,)
GL_GREEN_SCALE float 1.0 ( – ,)
GL_BLUE_SCALE float 1.0 ( – ,)
GL_ALPHA_SCALE float 1.0 ( – ,)
GL_DEPTH_SCALE float 1.0 ( – ,)
GL_RED_BIAS float 0.0 ( – ,)
GL_GREEN_BIAS float 0.0 ( – ,)
GL_BLUE_BIAS float 0.0 ( – ,)
GL_ALPHA_BIAS float 0.0 ( – ,)
GL_DEPTH_BIAS float 0.0 ( – ,)

If it was an RGB image I''d do GL_RED/GREEN/BLUE_SCALE and 1.5 to scale each RGB value by 1.5, but since your''s is 8bit I think you need to use INDEX_SHIFT and/or INDEX_OFFSET...

------------
- outRider -

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quote:
Original post by outRider
void glPixelTransferf(
GLenum pname,
GLfloat param
);

void glPixelTransferi(
GLenum pname,
GLint param
);

Pname Type Initial Value Valid Range
GL_MAP_COLOR Boolean false true/false
GL_MAP_STENCIL Boolean false true/false
GL_INDEX_SHIFT integer 0 ( – ,)
GL_INDEX_OFFSET integer 0 ( – ,)
GL_RED_SCALE float 1.0 ( – ,)
GL_GREEN_SCALE float 1.0 ( – ,)
GL_BLUE_SCALE float 1.0 ( – ,)
GL_ALPHA_SCALE float 1.0 ( – ,)
GL_DEPTH_SCALE float 1.0 ( – ,)
GL_RED_BIAS float 0.0 ( – ,)
GL_GREEN_BIAS float 0.0 ( – ,)
GL_BLUE_BIAS float 0.0 ( – ,)
GL_ALPHA_BIAS float 0.0 ( – ,)
GL_DEPTH_BIAS float 0.0 ( – ,)

If it was an RGB image I''d do GL_RED/GREEN/BLUE_SCALE and 1.5 to scale each RGB value by 1.5, but since your''s is 8bit I think you need to use INDEX_SHIFT and/or INDEX_OFFSET...

------------
- outRider -


I would like to thank you for your help. It works !!!

Best regards,
Zvika Vered.

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