{"id":25247,"url":"https://patchwork.libcamera.org/api/patches/25247/?format=json","web_url":"https://patchwork.libcamera.org/patch/25247/","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":"<20251127023739.179652-11-bryan.odonoghue@linaro.org>","date":"2025-11-27T02:37:25","name":"[v5,10/24] libcamera: shaders: Add support for contrast","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"206add1a595e3ba2b211f99d100fde0161161c03","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/25247/mbox/","series":[{"id":5617,"url":"https://patchwork.libcamera.org/api/series/5617/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5617","date":"2025-11-27T02:37:15","name":"Add GLES 2.0 GPUISP to libcamera","version":5,"mbox":"https://patchwork.libcamera.org/series/5617/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/25247/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/25247/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 9168EC0F2A\n\tfor ;\n\tThu, 27 Nov 2025 02:38:12 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 3EF3E60AD0;\n\tThu, 27 Nov 2025 03:38:12 +0100 (CET)","from mail-wm1-x332.google.com (mail-wm1-x332.google.com\n\t[IPv6:2a00:1450:4864:20::332])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 3626560A8B\n\tfor ;\n\tThu, 27 Nov 2025 03:38:09 +0100 (CET)","by mail-wm1-x332.google.com with SMTP id\n\t5b1f17b1804b1-47118259fd8so2250385e9.3\n\tfor ;\n\tWed, 26 Nov 2025 18:38:09 -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\t5b1f17b1804b1-4790552c3c9sm58186345e9.0.2025.11.26.18.38.06\n\t(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n\tWed, 26 Nov 2025 18:38:07 -0800 (PST)"],"Authentication-Results":"lancelot.ideasonboard.com; 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\n\tWed, 26 Nov 2025 18:38:08 -0800 (PST)","From":"Bryan O'Donoghue ","To":"libcamera-devel@lists.libcamera.org","Cc":"pavel@ucw.cz, Bryan O'Donoghue ,\n\tMilan Zamazal ","Subject":"[PATCH v5 10/24] libcamera: shaders: Add support for contrast","Date":"Thu, 27 Nov 2025 02:37:25 +0000","Message-ID":"<20251127023739.179652-11-bryan.odonoghue@linaro.org>","X-Mailer":"git-send-email 2.51.2","In-Reply-To":"<20251127023739.179652-1-bryan.odonoghue@linaro.org>","References":"<20251127023739.179652-1-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 \nSigned-off-by: Bryan O'Donoghue \n---\n src/libcamera/shaders/bayer_1x_packed.frag | 19 +++++++++++++++++++\n src/libcamera/shaders/bayer_unpacked.frag | 19 +++++++++++++++++++\n 2 files changed, 38 insertions(+)","diff":"diff --git a/src/libcamera/shaders/bayer_1x_packed.frag b/src/libcamera/shaders/bayer_1x_packed.frag\nindex 069b880ff..741896d01 100644\n--- a/src/libcamera/shaders/bayer_1x_packed.frag\n+++ b/src/libcamera/shaders/bayer_1x_packed.frag\n@@ -71,6 +71,19 @@ uniform sampler2D blue_param;\n uniform mat3 ccm;\n uniform vec3 blacklevel;\n uniform float gamma;\n+uniform float contrast;\n+\n+float apply_contrast(float normalise, float contrast_in)\n+{\n+\t// Convert 0..2 contrast to 0..infinity; avoid actual infinity at tan(pi/2)\n+\tfloat contrastExp = tan(clamp(contrast_in * 0.78539816339744830962, 0.0, 1.5707963267948966 - 0.00001));\n+\n+\t// Apply simple S-curve\n+\tif (normalise < 0.5)\n+\t\treturn 0.5 * pow(normalise / 0.5, contrastExp);\n+\telse\n+\t\treturn 1.0 - 0.5 * pow((1.0 - normalise) / 0.5, contrastExp);\n+}\n \n void main(void)\n {\n@@ -266,6 +279,12 @@ 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/* Contrast */\n+\trgb = clamp(rgb, 0.0, 1.0);\n+\trgb.r = apply_contrast(rgb.r, contrast);\n+\trgb.g = apply_contrast(rgb.g, contrast);\n+\trgb.b = apply_contrast(rgb.b, contrast);\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 86bf2c31c..43ed99e33 100644\n--- a/src/libcamera/shaders/bayer_unpacked.frag\n+++ b/src/libcamera/shaders/bayer_unpacked.frag\n@@ -30,6 +30,19 @@ varying vec4 xCoord;\n uniform mat3 ccm;\n uniform vec3 blacklevel;\n uniform float gamma;\n+uniform float contrast;\n+\n+float apply_contrast(float normalise, float contrast_in)\n+{\n+ // Convert 0..2 contrast to 0..infinity; avoid actual infinity at tan(pi/2)\n+ float contrastExp = tan(clamp(contrast_in * 0.78539816339744830962, 0.0, 1.5707963267948966 - 0.00001));\n+\n+ // Apply simple S-curve\n+ if (normalise < 0.5)\n+ return 0.5 * pow(normalise / 0.5, contrastExp);\n+ else\n+ return 1.0 - 0.5 * pow((1.0 - normalise) / 0.5, contrastExp);\n+}\n \n void main(void) {\n vec3 rgb;\n@@ -161,6 +174,12 @@ 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+ /* Contrast */\n+ rgb = clamp(rgb, 0.0, 1.0);\n+ rgb.r = apply_contrast(rgb.r, contrast);\n+ rgb.g = apply_contrast(rgb.g, contrast);\n+ rgb.b = apply_contrast(rgb.b, contrast);\n+\n /* Apply gamma after colour correction */\n rgb = pow(rgb, vec3(gamma));\n \n","prefixes":["v5","10/24"]}