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594 jab 1 
/**
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 * @file image_helper.h
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 * @brief Image helper functions
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 */
369 jab 5 
/*
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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	*/