116 lines
2.2 KiB
C
116 lines
2.2 KiB
C
/*
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Jonathan Dummer
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Image helper functions
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MIT license
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*/
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#ifndef HEADER_IMAGE_HELPER
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#define HEADER_IMAGE_HELPER
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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This function upscales an image.
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Not to be used to create MIPmaps,
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but to make it square,
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or to make it a power-of-two sized.
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**/
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int
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up_scale_image
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(
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const unsigned char* const orig,
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int width, int height, int channels,
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unsigned char* resampled,
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int resampled_width, int resampled_height
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);
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/**
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This function downscales an image.
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Used for creating MIPmaps,
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the incoming image should be a
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power-of-two sized.
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**/
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int
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mipmap_image
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(
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const unsigned char* const orig,
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int width, int height, int channels,
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unsigned char* resampled,
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int block_size_x, int block_size_y
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);
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/**
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This function takes the RGB components of the image
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and scales each channel from [0,255] to [16,235].
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This makes the colors "Safe" for display on NTSC
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displays. Note that this is _NOT_ a good idea for
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loading images like normal- or height-maps!
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**/
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int
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scale_image_RGB_to_NTSC_safe
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(
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unsigned char* orig,
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int width, int height, int channels
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);
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/**
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This function takes the RGB components of the image
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and converts them into YCoCg. 3 components will be
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re-ordered to CoYCg (for optimum DXT1 compression),
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while 4 components will be ordered CoCgAY (for DXT5
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compression).
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**/
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int
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convert_RGB_to_YCoCg
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(
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unsigned char* orig,
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int width, int height, int channels
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);
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/**
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This function takes the YCoCg components of the image
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and converts them into RGB. See above.
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**/
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int
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convert_YCoCg_to_RGB
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(
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unsigned char* orig,
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int width, int height, int channels
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);
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/**
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Converts an HDR image from an array
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of unsigned chars (RGBE) to RGBdivA
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\return 0 if failed, otherwise returns 1
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**/
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int
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RGBE_to_RGBdivA
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(
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unsigned char *image,
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int width, int height,
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int rescale_to_max
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);
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/**
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Converts an HDR image from an array
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of unsigned chars (RGBE) to RGBdivA2
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\return 0 if failed, otherwise returns 1
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**/
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int
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RGBE_to_RGBdivA2
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(
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unsigned char *image,
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int width, int height,
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int rescale_to_max
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);
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#ifdef __cplusplus
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}
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#endif
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#endif /* HEADER_IMAGE_HELPER */
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