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Added support for 8-bit grayscale output to fmt2bmp() for frame2bmp() #430

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Merged
merged 2 commits into from
Aug 23, 2022
Merged

Added support for 8-bit grayscale output to fmt2bmp() for frame2bmp() #430

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73ed44b
Added support for 8-bit grayscale output to fmt2bmp() for frame2bmp()
devellison Jul 30, 2022
1d24e8d
Merge branch 'master' into grayscale_fixes
devellison Aug 13, 2022
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58 changes: 35 additions & 23 deletions conversions/to_bmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -302,7 +302,13 @@ bool fmt2bmp(uint8_t *src, size_t src_len, uint16_t width, uint16_t height, pixf
*out_len = 0;

int pix_count = width*height;
size_t out_size = (pix_count * 3) + BMP_HEADER_LEN;

// With BMP, 8-bit greyscale requires a palette.
// For a 640x480 image though, that's a savings
// over going RGB-24.
int bpp = (format == PIXFORMAT_GRAYSCALE) ? 1 : 3;
int palette_size = (format == PIXFORMAT_GRAYSCALE) ? 4 * 256 : 0;
size_t out_size = (pix_count * bpp) + BMP_HEADER_LEN + palette_size;
uint8_t * out_buf = (uint8_t *)_malloc(out_size);
if(!out_buf) {
ESP_LOGE(TAG, "_malloc failed! %u", out_size);
Expand All @@ -314,45 +320,51 @@ bool fmt2bmp(uint8_t *src, size_t src_len, uint16_t width, uint16_t height, pixf
bmp_header_t * bitmap = (bmp_header_t*)&out_buf[2];
bitmap->reserved = 0;
bitmap->filesize = out_size;
bitmap->fileoffset_to_pixelarray = BMP_HEADER_LEN;
bitmap->fileoffset_to_pixelarray = BMP_HEADER_LEN + palette_size;
bitmap->dibheadersize = 40;
bitmap->width = width;
bitmap->height = -height;//set negative for top to bottom
bitmap->planes = 1;
bitmap->bitsperpixel = 24;
bitmap->bitsperpixel = bpp * 8;
bitmap->compression = 0;
bitmap->imagesize = pix_count * 3;
bitmap->imagesize = pix_count * bpp;
bitmap->ypixelpermeter = 0x0B13 ; //2835 , 72 DPI
bitmap->xpixelpermeter = 0x0B13 ; //2835 , 72 DPI
bitmap->numcolorspallette = 0;
bitmap->mostimpcolor = 0;

uint8_t * rgb_buf = out_buf + BMP_HEADER_LEN;
uint8_t * palette_buf = out_buf + BMP_HEADER_LEN;
uint8_t * pix_buf = palette_buf + palette_size;
uint8_t * src_buf = src;

if (palette_size > 0) {
// Grayscale palette
for (int i = 0; i < 256; ++i) {
for (int j = 0; j < 3; ++j) {
*palette_buf = i;
palette_buf++;
}
// Reserved / alpha channel.
*palette_buf = 0;
palette_buf++;
}
}

//convert data to RGB888
if(format == PIXFORMAT_RGB888) {
memcpy(rgb_buf, src_buf, pix_count*3);
memcpy(pix_buf, src_buf, pix_count*3);
} else if(format == PIXFORMAT_RGB565) {
int i;
uint8_t hb, lb;
for(i=0; i<pix_count; i++) {
hb = *src_buf++;
lb = *src_buf++;
*rgb_buf++ = (lb & 0x1F) << 3;
*rgb_buf++ = (hb & 0x07) << 5 | (lb & 0xE0) >> 3;
*rgb_buf++ = hb & 0xF8;
*pix_buf++ = (lb & 0x1F) << 3;
*pix_buf++ = (hb & 0x07) << 5 | (lb & 0xE0) >> 3;
*pix_buf++ = hb & 0xF8;
}
} else if(format == PIXFORMAT_GRAYSCALE) {
int i;
uint8_t b;
for(i=0; i<pix_count; i++) {
b = *src_buf++;
*rgb_buf++ = b;
*rgb_buf++ = b;
*rgb_buf++ = b;
}
memcpy(pix_buf, src_buf, pix_count);
} else if(format == PIXFORMAT_YUV422) {
int i, maxi = pix_count / 2;
uint8_t y0, y1, u, v;
Expand All @@ -364,14 +376,14 @@ bool fmt2bmp(uint8_t *src, size_t src_len, uint16_t width, uint16_t height, pixf
v = *src_buf++;

yuv2rgb(y0, u, v, &r, &g, &b);
*rgb_buf++ = b;
*rgb_buf++ = g;
*rgb_buf++ = r;
*pix_buf++ = b;
*pix_buf++ = g;
*pix_buf++ = r;

yuv2rgb(y1, u, v, &r, &g, &b);
*rgb_buf++ = b;
*rgb_buf++ = g;
*rgb_buf++ = r;
*pix_buf++ = b;
*pix_buf++ = g;
*pix_buf++ = r;
}
}
*out = out_buf;
Expand Down