{"id":25664,"url":"https://patchwork.libcamera.org/api/patches/25664/?format=json","web_url":"https://patchwork.libcamera.org/patch/25664/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260106170059.56193-12-bryan.odonoghue@linaro.org>","date":"2026-01-06T17:00:46","name":"[v11,11/24] libcamera: shaders: Add support for contrast","commit_ref":"e4effc1e3010211ea5f815f17ebac45b0dbdbd42","pull_url":null,"state":"accepted","archived":false,"hash":"f854a2739fe98e72907eff354a38e7735bf1ffc1","submitter":{"id":175,"url":"https://patchwork.libcamera.org/api/people/175/?format=json","name":"Bryan O'Donoghue","email":"bryan.odonoghue@linaro.org"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/25664/mbox/","series":[{"id":5689,"url":"https://patchwork.libcamera.org/api/series/5689/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5689","date":"2026-01-06T17:00:35","name":"Add GLES 2.0 GPUISP to libcamera","version":10,"mbox":"https://patchwork.libcamera.org/series/5689/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/25664/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/25664/checks/","tags":{},"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 51842C3213\n\tfor ;\n\tTue, 6 Jan 2026 17:01:21 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 19C606200C;\n\tTue, 6 Jan 2026 18:01:21 +0100 (CET)","from mail-wr1-x434.google.com (mail-wr1-x434.google.com\n\t[IPv6:2a00:1450:4864:20::434])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id A77CC61FF4\n\tfor ;\n\tTue, 6 Jan 2026 18:01:16 +0100 (CET)","by mail-wr1-x434.google.com with SMTP id\n\tffacd0b85a97d-42fbc305552so816362f8f.0\n\tfor ;\n\tTue, 06 Jan 2026 09:01:16 -0800 (PST)","from inspiron14p-linux.ht.home (188-141-3-146.dynamic.upc.ie.\n\t[188.141.3.146]) by smtp.gmail.com with ESMTPSA id\n\tffacd0b85a97d-432bd0dadcfsm5515322f8f.3.2026.01.06.09.01.14\n\t(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n\tTue, 06 Jan 2026 09:01:15 -0800 (PST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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\n\tTue, 06 Jan 2026 09:01:15 -0800 (PST)","From":"Bryan O'Donoghue ","To":"libcamera-devel@lists.libcamera.org","Cc":"pavel@ucw.cz, Bryan O'Donoghue ,\n\tMilan Zamazal ","Subject":"[PATCH v11 11/24] libcamera: shaders: Add support for contrast","Date":"Tue, 6 Jan 2026 17:00:46 +0000","Message-ID":"<20260106170059.56193-12-bryan.odonoghue@linaro.org>","X-Mailer":"git-send-email 2.52.0","In-Reply-To":"<20260106170059.56193-1-bryan.odonoghue@linaro.org>","References":"<20260106170059.56193-1-bryan.odonoghue@linaro.org>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-BeenThere":"libcamera-devel@lists.libcamera.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"Apply contrast after black-level and CCM operations.\n\nSuggested-by: Milan Zamazal \nReviewed-by: Milan Zamazal \nSigned-off-by: Bryan O'Donoghue \n---\n src/libcamera/shaders/bayer_1x_packed.frag | 19 +++++++++++++++++++\n src/libcamera/shaders/bayer_unpacked.frag | 18 ++++++++++++++++++\n 2 files changed, 37 insertions(+)","diff":"diff --git a/src/libcamera/shaders/bayer_1x_packed.frag b/src/libcamera/shaders/bayer_1x_packed.frag\nindex 77d9fbfa7..23747f78a 100644\n--- a/src/libcamera/shaders/bayer_1x_packed.frag\n+++ b/src/libcamera/shaders/bayer_1x_packed.frag\n@@ -68,6 +68,16 @@ uniform sampler2D tex_y;\n uniform mat3 ccm;\n uniform vec3 blacklevel;\n uniform float gamma;\n+uniform float contrastExp;\n+\n+float apply_contrast(float value)\n+{\n+\t// Apply simple S-curve\n+\tif (value < 0.5)\n+\t\treturn 0.5 * pow(value / 0.5, contrastExp);\n+\telse\n+\t\treturn 1.0 - 0.5 * pow((1.0 - value) / 0.5, contrastExp);\n+}\n \n void main(void)\n {\n@@ -261,6 +271,15 @@ void main(void)\n \trgb.g = (rin * ccm[1][0]) + (gin * ccm[1][1]) + (bin * ccm[1][2]);\n \trgb.b = (rin * ccm[2][0]) + (gin * ccm[2][1]) + (bin * ccm[2][2]);\n \n+\t/*\n+\t * Contrast\n+\t * contrastExp 0..2 contrast to 0..infinity; avoid actual infinity at tan(pi/2)\n+\t */\n+\trgb = clamp(rgb, 0.0, 1.0);\n+\trgb.r = apply_contrast(rgb.r);\n+\trgb.g = apply_contrast(rgb.g);\n+\trgb.b = apply_contrast(rgb.b);\n+\n \t/* Apply gamma after colour correction */\n \trgb = pow(rgb, vec3(gamma));\n \ndiff --git a/src/libcamera/shaders/bayer_unpacked.frag b/src/libcamera/shaders/bayer_unpacked.frag\nindex aba11a87f..af4a30c4b 100644\n--- a/src/libcamera/shaders/bayer_unpacked.frag\n+++ b/src/libcamera/shaders/bayer_unpacked.frag\n@@ -27,6 +27,16 @@ varying vec4 xCoord;\n uniform mat3 ccm;\n uniform vec3 blacklevel;\n uniform float gamma;\n+uniform float contrastExp;\n+\n+float apply_contrast(float value)\n+{\n+ // Apply simple S-curve\n+ if (value < 0.5)\n+ return 0.5 * pow(value / 0.5, contrastExp);\n+ else\n+ return 1.0 - 0.5 * pow((1.0 - value) / 0.5, contrastExp);\n+}\n \n void main(void) {\n vec3 rgb;\n@@ -156,6 +166,14 @@ void main(void) {\n rgb.g = (rin * ccm[1][0]) + (gin * ccm[1][1]) + (bin * ccm[1][2]);\n rgb.b = (rin * ccm[2][0]) + (gin * ccm[2][1]) + (bin * ccm[2][2]);\n \n+ /*\n+ * Contrast\n+ */\n+ rgb = clamp(rgb, 0.0, 1.0);\n+ rgb.r = apply_contrast(rgb.r);\n+ rgb.g = apply_contrast(rgb.g);\n+ rgb.b = apply_contrast(rgb.b);\n+\n /* Apply gamma after colour correction */\n rgb = pow(rgb, vec3(gamma));\n \n","prefixes":["v11","11/24"]}