[libcamera-devel] [PATCH v4 2/4] libcamera: rkisp1: Crop on ISP before downscaling

[Jacopo Mondi]

Crop on the resizer sink pad before downscaling to the aspect ratio
of the desired output size.

Cropping the input frame to the output aspect ratio allows to maintain
the correct picture proportions, as otherwise downscaling would change
the image geometry.

Signed-off-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
---
 src/libcamera/pipeline/rkisp1/rkisp1_path.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp b/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp
index 5079b268c464..5547cc32b6ca 100644
--- a/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp
+++ b/src/libcamera/pipeline/rkisp1/rkisp1_path.cpp
@@ -314,7 +314,10 @@ int RkISP1Path::configure(const StreamConfiguration &config,
 	if (ret < 0)
 		return ret;
 
-	Rectangle rect(0, 0, ispFormat.size);
+	/* Crop on the resizer input to maintain FOV before downscaling */
+	Size ispCrop = inputFormat.size.boundedToAspectRatio(config.size)
+				       .alignedUpTo(2, 2);
+	Rectangle rect(ispCrop);
 	ret = resizer_->setSelection(0, V4L2_SEL_TGT_CROP, &rect);
 	if (ret < 0)
 		return ret;
-- 
2.40.0