Skip to content

Add configurable RGB565 byte order support to JPEG encoding #820

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Nov 19, 2025
+27 −3
Merged

Add configurable RGB565 byte order support to JPEG encoding #820

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 11 additions & 0 deletions conversions/include/img_converters.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,17 @@ bool fmt2rgb888(const uint8_t *src_buf, size_t src_len, pixformat_t format, uint
#define JPG_SCALE_MAX JPEG_IMAGE_SCALE_1_8
bool jpg2rgb565(const uint8_t *src, size_t src_len, uint8_t * out, esp_jpeg_image_scale_t scale);

/**
* @brief Configure RGB565 input byte order for JPEG encoding.
*
* Controls how RGB565 source pixel data is interpreted before JPEG conversion.
* By default, the encoder assumes big-endian byte order (MSB first), which
* matches most ESP32 camera and frame buffer outputs.
*
* @param enable True to use big-endian RGB565 (default), false for little-endian.
*/
void jpgSetRgb565BE(bool enable);

#ifdef __cplusplus
}
#endif
Expand Down
19 changes: 16 additions & 3 deletions conversions/to_jpg.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,8 @@
static const char* TAG = "to_jpg";
#endif

static bool rgb565_big_endian = true;

static void *_malloc(size_t size)
{
void * res = malloc(size);
Expand Down Expand Up @@ -60,9 +62,15 @@ static IRAM_ATTR void convert_line_format(uint8_t * src, pixformat_t format, uin
l = width * 2;
src += l * line;
for(i=0; i<l; i+=2) {
dst[o++] = src[i] & 0xF8;
dst[o++] = (src[i] & 0x07) << 5 | (src[i+1] & 0xE0) >> 3;
dst[o++] = (src[i+1] & 0x1F) << 3;
if (rgb565_big_endian) {
dst[o++] = src[i] & 0xF8;
dst[o++] = (src[i] & 0x07) << 5 | (src[i+1] & 0xE0) >> 3;
dst[o++] = (src[i+1] & 0x1F) << 3;
} else {
dst[o++] = src[i+1] & 0xF8;
dst[o++] = (src[i+1] & 0x07) << 5 | (src[i] & 0xE0) >> 3;
dst[o++] = (src[i] & 0x1F) << 3;
}
}
} else if(format == PIXFORMAT_YUV422) {
uint8_t y0, y1, u, v;
Expand Down Expand Up @@ -233,3 +241,8 @@ bool frame2jpg(camera_fb_t * fb, uint8_t quality, uint8_t ** out, size_t * out_l
{
return fmt2jpg(fb->buf, fb->len, fb->width, fb->height, fb->format, quality, out, out_len);
}

void jpgSetRgb565BE(bool enable)
{
rgb565_big_endian = enable;
}
Loading