I was doing in front of a RTOS SCM system, LCD default image format is RGB565, but we are more interface, multi-picture resources, because the system only flash 4M

Picture too much out of the system results in a compile program flash.bin exceed 4M, is not conducive to expansion.

Back to think of compressed images, our image is an array of resources RGB565, and a 320 * 320 * 320 * 320 images have 2 bytes, nearly 200KB.

Relatively large.

Later compressed into rgb332, one pixel is one byte. You can save half the space.

Example code:

int image_convert_rgb565_to_rgb332(uint8_t *rgb565_src, uint8_t *rgb332_dst,uint32_t src_w,uint32_t src_h)
{
    uint32_t i,j;
    uint16_t *psrc_temp;
    uint8_t *pdst_temp;
    if (!rgb565_src || !rgb332_dst || src_w <= 0 || src_h <= 0) {
        LOG_I(x_screen,"image_convert_rgb565_to_rgb332 parameter error\n");
        return -1; 
    }   
    psrc_temp = (uint16_t *)rgb565_src;
    pdst_temp = (uint8_t *)rgb332_dst;
    for (i = 0; i < src_h; i++) {
        for (j = 0; j < src_w; j++) {
            *pdst_temp = ((*psrc_temp >> 13) << 5) //r 
                | ((*psrc_temp >> 8 & 0x07) << 2) //g 
                | (*psrc_temp >> 3 & 0x03); //b 
            pdst_temp++;
            psrc_temp++;
        }
    }   
    return 0;
}