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{
    "id": 25134,
    "url": "https://patchwork.libcamera.org/api/1.1/patches/25134/?format=api",
    "web_url": "https://patchwork.libcamera.org/patch/25134/",
    "project": {
        "id": 1,
        "url": "https://patchwork.libcamera.org/api/1.1/projects/1/?format=api",
        "name": "libcamera",
        "link_name": "libcamera",
        "list_id": "libcamera_core",
        "list_email": "libcamera-devel@lists.libcamera.org",
        "web_url": "",
        "scm_url": "",
        "webscm_url": ""
    },
    "msgid": "<20251120233347.5046-11-bryan.odonoghue@linaro.org>",
    "date": "2025-11-20T23:33:34",
    "name": "[v4,10/23] libcamera: shaders: Add support for contrast",
    "commit_ref": null,
    "pull_url": null,
    "state": "superseded",
    "archived": false,
    "hash": "491277a5a07ef1e185093f98361c1da86df1fb83",
    "submitter": {
        "id": 175,
        "url": "https://patchwork.libcamera.org/api/1.1/people/175/?format=api",
        "name": "Bryan O'Donoghue",
        "email": "bryan.odonoghue@linaro.org"
    },
    "delegate": null,
    "mbox": "https://patchwork.libcamera.org/patch/25134/mbox/",
    "series": [
        {
            "id": 5600,
            "url": "https://patchwork.libcamera.org/api/1.1/series/5600/?format=api",
            "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=5600",
            "date": "2025-11-20T23:33:24",
            "name": "Add GLES 2.0 GPUISP to libcamera",
            "version": 4,
            "mbox": "https://patchwork.libcamera.org/series/5600/mbox/"
        }
    ],
    "comments": "https://patchwork.libcamera.org/api/patches/25134/comments/",
    "check": "pending",
    "checks": "https://patchwork.libcamera.org/api/patches/25134/checks/",
    "tags": {},
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        "From": "Bryan O'Donoghue <bryan.odonoghue@linaro.org>",
        "To": "libcamera-devel@lists.libcamera.org",
        "Cc": "pavel@ucw.cz, Bryan O'Donoghue <bryan.odonoghue@linaro.org>,\n\tMilan Zamazal <mzamazal@redhat.com>",
        "Subject": "[PATCH v4 10/23] libcamera: shaders: Add support for contrast",
        "Date": "Thu, 20 Nov 2025 23:33:34 +0000",
        "Message-ID": "<20251120233347.5046-11-bryan.odonoghue@linaro.org>",
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    },
    "content": "Apply contrast after black-level and CCM operations.\n\nSuggested-by: Milan Zamazal <mzamazal@redhat.com>\nSigned-off-by: Bryan O'Donoghue \n\n33905b0b43c989c89a177c0e27dcd1acc80e750a\n\nSigned-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>\n---\n .../internal/shaders/bayer_1x_packed.frag     | 19 +++++++++++++++++++\n .../internal/shaders/bayer_unpacked.frag      | 19 +++++++++++++++++++\n 2 files changed, 38 insertions(+)",
    "diff": "diff --git a/include/libcamera/internal/shaders/bayer_1x_packed.frag b/include/libcamera/internal/shaders/bayer_1x_packed.frag\nindex 069b880ff..741896d01 100644\n--- a/include/libcamera/internal/shaders/bayer_1x_packed.frag\n+++ b/include/libcamera/internal/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/include/libcamera/internal/shaders/bayer_unpacked.frag b/include/libcamera/internal/shaders/bayer_unpacked.frag\nindex 950a4733e..16262feb2 100644\n--- a/include/libcamera/internal/shaders/bayer_unpacked.frag\n+++ b/include/libcamera/internal/shaders/bayer_unpacked.frag\n@@ -30,6 +30,19 @@ varying vec4            xCoord;\n uniform mat3\t\tccm;\n uniform vec3\t\tblacklevel;\n uniform float\t\tgamma;\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     vec3 rgb;\n@@ -161,6 +174,12 @@ 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 \n",
    "prefixes": [
        "v4",
        "10/23"
    ]
}