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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   */