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{
    "id": 8978,
    "url": "https://patchwork.libcamera.org/api/1.1/patches/8978/?format=api",
    "web_url": "https://patchwork.libcamera.org/patch/8978/",
    "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": "<20200724145618.26304-4-david.plowman@raspberrypi.com>",
    "date": "2020-07-24T14:56:18",
    "name": "[libcamera-devel,v2,3/3] libcamera: qcam: Improve colour information in DNG files",
    "commit_ref": null,
    "pull_url": null,
    "state": "accepted",
    "archived": false,
    "hash": "654fe9f581b25278cad50c862bcd9964ddf69199",
    "submitter": {
        "id": 42,
        "url": "https://patchwork.libcamera.org/api/1.1/people/42/?format=api",
        "name": "David Plowman",
        "email": "david.plowman@raspberrypi.com"
    },
    "delegate": null,
    "mbox": "https://patchwork.libcamera.org/patch/8978/mbox/",
    "series": [
        {
            "id": 1138,
            "url": "https://patchwork.libcamera.org/api/1.1/series/1138/?format=api",
            "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=1138",
            "date": "2020-07-24T14:56:15",
            "name": "ColourCorrectionMatrix control",
            "version": 2,
            "mbox": "https://patchwork.libcamera.org/series/1138/mbox/"
        }
    ],
    "comments": "https://patchwork.libcamera.org/api/patches/8978/comments/",
    "check": "pending",
    "checks": "https://patchwork.libcamera.org/api/patches/8978/checks/",
    "tags": {},
    "headers": {
        "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>",
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        "X-Received": "by 2002:adf:c386:: with SMTP id p6mr8926727wrf.344.1595602600146;\n\tFri, 24 Jul 2020 07:56:40 -0700 (PDT)",
        "From": "David Plowman <david.plowman@raspberrypi.com>",
        "To": "libcamera-devel@lists.libcamera.org",
        "Date": "Fri, 24 Jul 2020 15:56:18 +0100",
        "Message-Id": "<20200724145618.26304-4-david.plowman@raspberrypi.com>",
        "X-Mailer": "git-send-email 2.20.1",
        "In-Reply-To": "<20200724145618.26304-1-david.plowman@raspberrypi.com>",
        "References": "<20200724145618.26304-1-david.plowman@raspberrypi.com>",
        "MIME-Version": "1.0",
        "Subject": "[libcamera-devel] [PATCH v2 3/3] libcamera: qcam: Improve colour\n\tinformation in DNG files",
        "X-BeenThere": "libcamera-devel@lists.libcamera.org",
        "X-Mailman-Version": "2.1.29",
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        "List-Id": "<libcamera-devel.lists.libcamera.org>",
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        "Errors-To": "libcamera-devel-bounces@lists.libcamera.org",
        "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>"
    },
    "content": "This patch improves the colour information recorded in DNG files using\nthe ColourCorrectionMatrix metadata for the image. Note that we are\nnot supplying a full calibration using two illuminants, nonetheless\nthe single matrix here appears to be respected by a number of tools.\n\nSigned-off-by: David Plowman <david.plowman@raspberrypi.com>\n---\n src/qcam/dng_writer.cpp | 138 ++++++++++++++++++++++++++++++++++++++++\n 1 file changed, 138 insertions(+)",
    "diff": "diff --git a/src/qcam/dng_writer.cpp b/src/qcam/dng_writer.cpp\nindex 61505d3..4f638ec 100644\n--- a/src/qcam/dng_writer.cpp\n+++ b/src/qcam/dng_writer.cpp\n@@ -34,6 +34,97 @@ struct FormatInfo {\n \t\t\t      unsigned int stride);\n };\n \n+struct Matrix3d {\n+\tMatrix3d()\n+\t{\n+\t}\n+\n+\tMatrix3d(float m0, float m1, float m2,\n+\t\t float m3, float m4, float m5,\n+\t\t float m6, float m7, float m8)\n+\t{\n+\t\tm[0] = m0, m[1] = m1, m[2] = m2;\n+\t\tm[3] = m3, m[4] = m4, m[5] = m5;\n+\t\tm[6] = m6, m[7] = m7, m[8] = m8;\n+\t}\n+\n+\tMatrix3d(Span<const float> const &span)\n+\t\t: Matrix3d(span[0], span[1], span[2],\n+\t\t\t   span[3], span[4], span[5],\n+\t\t\t   span[6], span[7], span[8])\n+\t{\n+\t}\n+\n+\tstatic Matrix3d diag(float diag0, float diag1, float diag2)\n+\t{\n+\t\treturn Matrix3d(diag0, 0, 0, 0, diag1, 0, 0, 0, diag2);\n+\t}\n+\n+\tstatic Matrix3d identity()\n+\t{\n+\t\treturn Matrix3d(1, 0, 0, 0, 1, 0, 0, 0, 1);\n+\t}\n+\n+\tMatrix3d transpose() const\n+\t{\n+\t\treturn { m[0], m[3], m[6], m[1], m[4], m[7], m[2], m[5], m[8] };\n+\t}\n+\n+\tMatrix3d cofactors() const\n+\t{\n+\t\treturn { m[4] * m[8] - m[5] * m[7],\n+\t\t\t -(m[3] * m[8] - m[5] * m[6]),\n+\t\t\t m[3] * m[7] - m[4] * m[6],\n+\t\t\t -(m[1] * m[8] - m[2] * m[7]),\n+\t\t\t m[0] * m[8] - m[2] * m[6],\n+\t\t\t -(m[0] * m[7] - m[1] * m[6]),\n+\t\t\t m[1] * m[5] - m[2] * m[4],\n+\t\t\t -(m[0] * m[5] - m[2] * m[3]),\n+\t\t\t m[0] * m[4] - m[1] * m[3] };\n+\t}\n+\n+\tMatrix3d adjugate() const\n+\t{\n+\t\treturn cofactors().transpose();\n+\t}\n+\n+\tfloat determinant() const\n+\t{\n+\t\treturn m[0] * (m[4] * m[8] - m[5] * m[7]) -\n+\t\t       m[1] * (m[3] * m[8] - m[5] * m[6]) +\n+\t\t       m[2] * (m[3] * m[7] - m[4] * m[6]);\n+\t}\n+\n+\tMatrix3d inverse() const\n+\t{\n+\t\treturn adjugate() * (1.0 / determinant());\n+\t}\n+\n+\tMatrix3d operator*(Matrix3d const &other) const\n+\t{\n+\t\tMatrix3d result;\n+\t\tfor (unsigned int i = 0; i < 3; i++) {\n+\t\t\tfor (unsigned int j = 0; j < 3; j++) {\n+\t\t\t\tresult.m[i * 3 + j] =\n+\t\t\t\t\tm[i * 3 + 0] * other.m[0 + j] +\n+\t\t\t\t\tm[i * 3 + 1] * other.m[3 + j] +\n+\t\t\t\t\tm[i * 3 + 2] * other.m[6 + j];\n+\t\t\t}\n+\t\t}\n+\t\treturn result;\n+\t}\n+\n+\tMatrix3d operator*(float f) const\n+\t{\n+\t\tMatrix3d result;\n+\t\tfor (unsigned int i = 0; i < 9; i++)\n+\t\t\tresult.m[i] = m[i] * f;\n+\t\treturn result;\n+\t}\n+\n+\tfloat m[9];\n+};\n+\n void packScanlineSBGGR10P(void *output, const void *input, unsigned int width)\n {\n \tconst uint8_t *in = static_cast<const uint8_t *>(input);\n@@ -315,6 +406,53 @@ int DNGWriter::write(const char *filename, const Camera *camera,\n \tTIFFSetField(tif, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);\n \tTIFFSetField(tif, TIFFTAG_SAMPLEFORMAT, SAMPLEFORMAT_UINT);\n \n+\t/*\n+\t * Fill in some reasonable colour information in the DNG. We supply\n+\t * the \"neutral\" colour values which determine the white balance, and the\n+\t * \"ColorMatrix1\" which converts XYZ to (un-white-balanced) camera RGB.\n+\t * Note that this is not a \"proper\" colour calibration for the DNG,\n+\t * nonetheless, many tools should be able to render the colours better.\n+\t */\n+\tfloat neutral[3] = { 1, 1, 1 };\n+\tMatrix3d wbGain = Matrix3d::identity();\n+\t/* From http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html */\n+\tconst Matrix3d rgb2xyz(0.4124564, 0.3575761, 0.1804375,\n+\t\t\t       0.2126729, 0.7151522, 0.0721750,\n+\t\t\t       0.0193339, 0.1191920, 0.9503041);\n+\tMatrix3d ccm = Matrix3d::identity();\n+\t/*\n+\t * Pick a reasonable number eps to protect against singularities. It\n+\t * should be comfortably larger than the point at which we run into\n+\t * numerical trouble, yet smaller than any plausible gain that we might\n+\t * apply to a colour, either explicitly or as part of the colour matrix.\n+\t */\n+\tconst double eps = 1e-2;\n+\n+\tif (metadata.contains(controls::ColourGains)) {\n+\t\tSpan<const float> const &colourGains = metadata.get(controls::ColourGains);\n+\t\tif (colourGains[0] > eps && colourGains[1] > eps) {\n+\t\t\twbGain = Matrix3d::diag(colourGains[0], 1, colourGains[1]);\n+\t\t\tneutral[0] = 1.0 / colourGains[0]; /* red */\n+\t\t\tneutral[2] = 1.0 / colourGains[1]; /* blue */\n+\t\t}\n+\t}\n+\tif (metadata.contains(controls::ColourCorrectionMatrix)) {\n+\t\tSpan<const float> const &coeffs = metadata.get(controls::ColourCorrectionMatrix);\n+\t\tMatrix3d ccm_supplied(coeffs);\n+\t\tif (ccm_supplied.determinant() > eps)\n+\t\t\tccm = ccm_supplied;\n+\t}\n+\n+\t/*\n+\t * rgb2xyz is known to be invertible, and we've ensured above that both\n+\t * the ccm and wbGain matrices are non-singular, so the product of all\n+\t * three is guaranteed to be invertible too.\n+\t */\n+\tMatrix3d colorMatrix1 = (rgb2xyz * ccm * wbGain).inverse();\n+\n+\tTIFFSetField(tif, TIFFTAG_COLORMATRIX1, 9, colorMatrix1.m);\n+\tTIFFSetField(tif, TIFFTAG_ASSHOTNEUTRAL, 3, neutral);\n+\n \t/*\n \t * Reserve space for the SubIFD and ExifIFD tags, pointing to the IFD\n \t * for the raw image and EXIF data respectively. The real offsets will\n",
    "prefixes": [
        "libcamera-devel",
        "v2",
        "3/3"
    ]
}