diff options
| author | Laurent Pinchart <laurent.pinchart@ideasonboard.com> | 2025-04-04 04:51:46 +0300 |
|---|---|---|
| committer | Laurent Pinchart <laurent.pinchart@ideasonboard.com> | 2025-04-05 03:02:33 +0300 |
| commit | 14ed7467627ed3ad80030f8d97601bbcf78a6907 (patch) | |
| tree | 94f94b35a1b523f506749770218ced5837f3e07e | |
| parent | 6df1ad61158e9c2744786193619b873b3dedcd6b (diff) | |
gen-image: Round sub-sampled chroma towards zero
Based on tests, the VSP1 hardware seems to round averaged chroma values
towards 0 when subsampling YUV formats. Replicate the same calculation
in gen-image.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
| -rw-r--r-- | src/gen-image.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/src/gen-image.c b/src/gen-image.c index 170d694..d053d79 100644 --- a/src/gen-image.c +++ b/src/gen-image.c @@ -618,8 +618,15 @@ static void image_format_yuv_packed(const struct image *input, struct image *out o_c[2*x + u_offset] = idata[3*x + 1]; o_c[2*x + v_offset] = idata[3*x + 2]; } else { - o_c[2*x + u_offset] = (idata[3*x + 1] + idata[3*x + 4]) / 2; - o_c[2*x + v_offset] = (idata[3*x + 2] + idata[3*x + 5]) / 2; + unsigned int u = idata[3*x + 1] + idata[3*x + 4]; + unsigned int v = idata[3*x + 2] + idata[3*x + 5]; + + /* Round towards the middle value. */ + u += u < 0x100 ? 1 : 0; + v += v < 0x100 ? 1 : 0; + + o_c[2*x + u_offset] = u / 2; + o_c[2*x + v_offset] = v / 2; } } @@ -674,8 +681,15 @@ static void image_format_yuv_planar(const struct image *input, struct image *out } } else { for (x = 0; x < output->width; x += xsub) { - o_u[x*c_stride/xsub] = (idata[3*x + 1] + idata[3*x + 4]) / 2; - o_v[x*c_stride/xsub] = (idata[3*x + 2] + idata[3*x + 5]) / 2; + unsigned int u = idata[3*x + 1] + idata[3*x + 4]; + unsigned int v = idata[3*x + 2] + idata[3*x + 5]; + + /* Round towards the middle value. */ + u += u < 0x100 ? 1 : 0; + v += v < 0x100 ? 1 : 0; + + o_u[x*c_stride/xsub] = u / 2; + o_v[x*c_stride/xsub] = v / 2; } } |