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