[{"id":37506,"web_url":"https://patchwork.libcamera.org/comment/37506/","msgid":"<176777989223.3486172.13160471073173386920@ping.linuxembedded.co.uk>","date":"2026-01-07T09:58:12","subject":"Re: [PATCH v11 04/24] qcam: viewfinder_gl: Set no-op Bayer shader\n\tvalues","submitter":{"id":4,"url":"https://patchwork.libcamera.org/api/people/4/","name":"Kieran Bingham","email":"kieran.bingham@ideasonboard.com"},"content":"Quoting Bryan O'Donoghue (2026-01-06 17:00:39)\n> Populate qcam viewfinder_gl to set default Bayer values so that the\n> shaders can be used in their original mode without conditional compilation.\n> \n> Set an identity CCM, identity Black Level and set Gamma and Contrast to\n> 1.0f respectively.\n> \n> Once this change is made we can use the Bayer shaders in their original\n> format in qcam with raw streams.\n> \n> Reviewed-by: Milan Zamazal \n\nI don't really fully understand the magic of shaders here - but\neverything looks sensible, and once tested I'm fine with this being\nmerged so:\n\nReviewed-by: Kieran Bingham \n\n> Signed-off-by: Bryan O'Donoghue \n> ---\n> src/apps/qcam/viewfinder_gl.cpp | 26 ++++++++++++++++++++++++++\n> src/apps/qcam/viewfinder_gl.h | 12 ++++++++++++\n> 2 files changed, 38 insertions(+)\n> \n> diff --git a/src/apps/qcam/viewfinder_gl.cpp b/src/apps/qcam/viewfinder_gl.cpp\n> index 1554c94d5..0d06122f6 100644\n> --- a/src/apps/qcam/viewfinder_gl.cpp\n> +++ b/src/apps/qcam/viewfinder_gl.cpp\n> @@ -473,6 +473,10 @@ bool ViewFinderGL::createFragmentShader()\n> textureUniformSize_ = shaderProgram_.uniformLocation(\"tex_size\");\n> textureUniformStrideFactor_ = shaderProgram_.uniformLocation(\"stride_factor\");\n> textureUniformBayerFirstRed_ = shaderProgram_.uniformLocation(\"tex_bayer_first_red\");\n> + ccmUniformDataIn_ = shaderProgram_.uniformLocation(\"ccm\");\n> + blackLevelUniformDataIn_ = shaderProgram_.uniformLocation(\"blacklevel\");\n> + gammaUniformDataIn_ = shaderProgram_.uniformLocation(\"gamma\");\n> + contrastExpUniformDataIn_ = shaderProgram_.uniformLocation(\"contrastExp\");\n> \n> /* Create the textures. */\n> for (std::unique_ptr &texture : textures_) {\n> @@ -542,6 +546,16 @@ void ViewFinderGL::doRender()\n> /* Stride of the first plane, in pixels. */\n> unsigned int stridePixels;\n> \n> + /* Identity CCM */\n> + float ccm[] = { 1.0f, 0.0f, 0.0f,\n> + 0.0f, 1.0f, 0.0f,\n> + 0.0f, 0.0f, 1.0f };\n> +\n> + QMatrix3x3 qCcmMat(ccm);\n> +\n> + /* Black Level */\n> + QVector3D qBlackLevelVec(0.0f, 0.0f, 0.0f);\n> +\n> switch (format_) {\n> case libcamera::formats::NV12:\n> case libcamera::formats::NV21:\n> @@ -788,6 +802,18 @@ void ViewFinderGL::doRender()\n> * the generic stride factor to 1.0.\n> */\n> stridePixels = size_.width();\n> +\n> + /* Colour Correction Matrix */\n> + shaderProgram_.setUniformValue(ccmUniformDataIn_, qCcmMat);\n> +\n> + /* Black Level */\n> + shaderProgram_.setUniformValue(blackLevelUniformDataIn_, qBlackLevelVec);\n> +\n> + /* Gamma */\n> + shaderProgram_.setUniformValue(gammaUniformDataIn_, 1.0f);\n> +\n> + /* Contrast */\n> + shaderProgram_.setUniformValue(contrastExpUniformDataIn_, 1.0f);\n> break;\n> \n> default:\n> diff --git a/src/apps/qcam/viewfinder_gl.h b/src/apps/qcam/viewfinder_gl.h\n> index 23c657bcf..1aa85e4fc 100644\n> --- a/src/apps/qcam/viewfinder_gl.h\n> +++ b/src/apps/qcam/viewfinder_gl.h\n> @@ -103,5 +103,17 @@ private:\n> GLuint textureUniformBayerFirstRed_;\n> QPointF firstRed_;\n> \n> + /* Represent per-frame CCM as a uniform vector of floats 3 x 3 */\n> + GLint ccmUniformDataIn_;\n> +\n> + /* Black Level compensation */\n> + GLint blackLevelUniformDataIn_;\n> +\n> + /* Gamma */\n> + GLint gammaUniformDataIn_;\n> +\n> + /* Contrast */\n> + GLint contrastExpUniformDataIn_;\n> +\n> QMutex mutex_; /* Prevent concurrent access to image_ */\n> };\n> -- \n> 2.52.0\n>","headers":{"Return-Path":"","X-Original-To":"parsemail@patchwork.libcamera.org","Delivered-To":"parsemail@patchwork.libcamera.org","Received":["from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id 1423ABDCBF\n\tfor ;\n\tWed, 7 Jan 2026 09:58:18 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 1143661FBB;\n\tWed, 7 Jan 2026 10:58:17 +0100 (CET)","from perceval.ideasonboard.com (perceval.ideasonboard.com\n\t[213.167.242.64])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 6751761F61\n\tfor ;\n\tWed, 7 Jan 2026 10:58:15 +0100 (CET)","from pendragon.ideasonboard.com\n\t(cpc89244-aztw30-2-0-cust6594.18-1.cable.virginm.net [86.31.185.195])\n\tby perceval.ideasonboard.com (Postfix) with ESMTPSA id 9845773B;\n\tWed, 7 Jan 2026 10:57:53 +0100 (CET)"],"Authentication-Results":"lancelot.ideasonboard.com; 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