Add support for CD-I IFF images

README.md

@@ -357,6 +357,8 @@ The plugin supports the following image data:
   type 4.
 - FORM PBM: PBM is a chunky version of IFF pictures. It supports 8-bit images 
   with color map only.
+- FORM IMAG (Compact Disc-Interactive): It supports CLut4, CLut8 and DYuv
+  formats.
 - FOR4 CIMG (Maya Image File Format): It supports 24/48-bit RGB and 32/64-bit 
   RGBA images.
 

src/imageformats/chunks.cpp

@@ -311,10 +311,18 @@ IFFChunk::ChunkList IFFChunk::innerFromDevice(QIODevice *d, bool *ok, IFFChunk *
             chunk = QSharedPointer<IFFChunk>(new ICCNChunk());
         } else if (cid == ICCP_CHUNK) {
             chunk = QSharedPointer<IFFChunk>(new ICCPChunk());
+        } else if (cid == IDAT_CHUNK) {
+            chunk = QSharedPointer<IFFChunk>(new IDATChunk());
+        } else if (cid == IHDR_CHUNK) {
+            chunk = QSharedPointer<IFFChunk>(new IHDRChunk());
+        } else if (cid == IPAR_CHUNK) {
+            chunk = QSharedPointer<IFFChunk>(new IPARChunk());
         } else if (cid == NAME_CHUNK) {
             chunk = QSharedPointer<IFFChunk>(new NAMEChunk());
         } else if (cid == PCHG_CHUNK) {
             chunk = QSharedPointer<IFFChunk>(new PCHGChunk());
+        } else if (cid == PLTE_CHUNK) {
+            chunk = QSharedPointer<IFFChunk>(new PLTEChunk());
         } else if (cid == RAST_CHUNK) {
             chunk = QSharedPointer<IFFChunk>(new RASTChunk());
         } else if (cid == RGBA_CHUNK) {
@@ -1406,16 +1414,13 @@ bool FORMChunk::innerReadStructure(QIODevice *d)
         setChunks(IFFChunk::innerFromDevice(d, &ok, this));
     } else if (_type == RGBN_FORM_TYPE) {
         setChunks(IFFChunk::innerFromDevice(d, &ok, this));
+    } else if (_type == IMAG_FORM_TYPE) {
+        setChunks(IFFChunk::innerFromDevice(d, &ok, this));
     }
     return ok;
 }
 
-QByteArray FORMChunk::formType() const
-{
-    return _type;
-}
-
-QImage::Format FORMChunk::format() const
+QImage::Format FORMChunk::iffFormat() const
 {
     auto headers = IFFChunk::searchT<BMHDChunk>(chunks());
     if (headers.isEmpty()) {
@@ -1464,13 +1469,67 @@ QImage::Format FORMChunk::format() const
     return QImage::Format_Invalid;
 }
 
+QImage::Format FORMChunk::cdiFormat() const
+{
+    auto headers = IFFChunk::searchT<IHDRChunk>(chunks());
+    if (headers.isEmpty()) {
+        return QImage::Format_Invalid;
+    }
+
+    if (auto &&h = headers.first()) {
+        if (h->model() == IHDRChunk::Rgb555 && h->depth() == 16) { // no test case
+            return QImage::Format_RGB555;
+        }
+
+        if (h->depth() == 4) {
+            if (h->model() == IHDRChunk::CLut4 || h->model() == IHDRChunk::CLut3) { // CLut3: no test case
+                return QImage::Format_Indexed8;
+            }
+        }
+
+        if (h->depth() == 8) {
+            if (h->model() == IHDRChunk::CLut8 || h->model() == IHDRChunk::CLut7) { // CLut7: no test case
+                return QImage::Format_Indexed8;
+            }
+            if (h->model() == IHDRChunk::Rgb888) { // no test case
+                return FORMAT_RGB_8BIT;
+            }
+            if (h->model() == IHDRChunk::DYuv && h->yuvKind() == IHDRChunk::One) {
+                return FORMAT_RGB_8BIT;
+            }
+        }
+    }
+
+    return QImage::Format_Invalid;
+}
+
+QByteArray FORMChunk::formType() const
+{
+    return _type;
+}
+
+QImage::Format FORMChunk::format() const
+{
+    if (formType() == IMAG_FORM_TYPE) {
+        return cdiFormat();
+    }
+    return iffFormat();
+}
+
 QSize FORMChunk::size() const
 {
-    auto headers = IFFChunk::searchT<BMHDChunk>(chunks());
-    if (headers.isEmpty()) {
-        return {};
+    if (formType() == IMAG_FORM_TYPE) {
+        auto ihdrs = IFFChunk::searchT<IHDRChunk>(chunks());
+        if (!ihdrs.isEmpty()) {
+            return ihdrs.first()->size();
+        }
+    } else {
+        auto bmhds = IFFChunk::searchT<BMHDChunk>(chunks());
+        if (!bmhds.isEmpty()) {
+            return bmhds.first()->size();
+        }
     }
-    return headers.first()->size();
+    return {};
 }
 
 /* ******************
@@ -1583,6 +1642,8 @@ bool CATChunk::innerReadStructure(QIODevice *d)
         setChunks(IFFChunk::innerFromDevice(d, &ok, this));
     } else if (_type == RGBN_FORM_TYPE) {
         setChunks(IFFChunk::innerFromDevice(d, &ok, this));
+    } else if (_type == IMAG_FORM_TYPE) {
+        setChunks(IFFChunk::innerFromDevice(d, &ok, this));
     }
     return ok;
 }
@@ -2371,6 +2432,398 @@ bool XMP0Chunk::innerReadStructure(QIODevice *d)
 }
 
 
+/* ******************
+ * *** IHDR Chunk ***
+ * ****************** */
+
+IHDRChunk::~IHDRChunk()
+{
+
+}
+
+IHDRChunk::IHDRChunk()
+{
+
+}
+
+bool IHDRChunk::isValid() const
+{
+    if (dataBytes() < 14) {
+        return false;
+    }
+    return chunkId() == IHDRChunk::defaultChunkId();
+}
+
+qint32 IHDRChunk::width() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(1), data().at(0)));
+}
+
+qint32 IHDRChunk::height() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(5), data().at(4)));
+}
+
+QSize IHDRChunk::size() const
+{
+    return QSize(width(), height());
+}
+
+qint32 IHDRChunk::lineSize() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(3), data().at(2)));
+}
+
+quint16 IHDRChunk::depth() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(9), data().at(8)));
+}
+
+IHDRChunk::Model IHDRChunk::model() const
+{
+    if (!isValid()) {
+        return IHDRChunk::Model::Invalid;
+    }
+    return IHDRChunk::Model(ui16(data().at(7), data().at(6)));
+}
+
+IHDRChunk::DYuvKind IHDRChunk::yuvKind() const
+{
+    if (!isValid()) {
+        return IHDRChunk::DYuvKind::One;
+    }
+    return IHDRChunk::DYuvKind(data().at(10));
+}
+
+IHDRChunk::Yuv IHDRChunk::yuvStart() const
+{
+    if (!isValid()) {
+        return{};
+    }
+    return(Yuv(data().at(11), data().at(12), data().at(13)));
+}
+
+bool IHDRChunk::innerReadStructure(QIODevice *d)
+{
+    return cacheData(d);
+}
+
+
+/* ******************
+ * *** IPAR Chunk ***
+ * ****************** */
+
+IPARChunk::~IPARChunk()
+{
+
+}
+
+IPARChunk::IPARChunk()
+{
+
+}
+
+bool IPARChunk::isValid() const
+{
+    if (dataBytes() < 22) {
+        return false;
+    }
+    return chunkId() == IPARChunk::defaultChunkId();
+}
+
+qint32 IPARChunk::xOffset() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(1), data().at(0)));
+}
+
+qint32 IPARChunk::yOffset() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(3), data().at(2)));
+}
+
+double IPARChunk::aspectRatio() const
+{
+    if (!isValid()) {
+        return 1;
+    }
+    if (auto xr = ui16(data().at(5), data().at(4))) {
+        auto yr = double(ui16(data().at(7), data().at(6)));
+        return yr / xr;
+    }
+    return 1;
+}
+
+qint32 IPARChunk::xPage() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(9), data().at(8)));
+}
+
+qint32 IPARChunk::yPage() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(11), data().at(10)));
+}
+
+qint32 IPARChunk::xGrub() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(13), data().at(12)));
+}
+
+qint32 IPARChunk::yGrub() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return qint32(ui16(data().at(15), data().at(14)));
+}
+
+IPARChunk::Rgb IPARChunk::mask() const
+{
+    if (!isValid()) {
+        return {};
+    }
+    return Rgb(data().at(16), data().at(17), data().at(18));
+}
+
+IPARChunk::Rgb IPARChunk::transparency() const
+{
+    if (!isValid()) {
+        return {};
+    }
+    return Rgb(data().at(19), data().at(20), data().at(21));
+}
+
+bool IPARChunk::innerReadStructure(QIODevice *d)
+{
+    return cacheData(d);
+}
+
+
+/* ******************
+ * *** PLTE Chunk ***
+ * ****************** */
+
+PLTEChunk::~PLTEChunk()
+{
+
+}
+
+PLTEChunk::PLTEChunk()
+{
+
+}
+
+bool PLTEChunk::isValid() const
+{
+    if (dataBytes() < 4) {
+        return false;
+    }
+    if (dataBytes() - 4 < total() * 3) {
+        return false;
+    }
+    return chunkId() == PLTEChunk::defaultChunkId();
+}
+
+qint32 PLTEChunk::count() const
+{
+    if (!isValid()) {
+        return 0;
+    }
+    return total() - count();
+}
+
+qint32 PLTEChunk::offset() const
+{
+    return qint32(ui16(data().at(1), data().at(0)));
+}
+
+qint32 PLTEChunk::total() const
+{
+    return qint32(ui16(data().at(3), data().at(2)));
+}
+
+QList<QRgb> PLTEChunk::innerPalette() const
+{
+    if (!isValid()) {
+        return{};
+    }
+    QList<QRgb> l;
+    auto &&d = data();
+    for (qint32 i = offset(), n = total(); i < n; ++i) {
+        auto i3 = 4 + i * 3;
+        l << qRgb(d.at(i3), d.at(i3 + 1), d.at(i3 + 2));
+    }
+    return l;
+}
+
+
+/* ******************
+ * *** IDAT Chunk ***
+ * ****************** */
+
+IDATChunk::~IDATChunk()
+{
+
+}
+
+IDATChunk::IDATChunk()
+{
+
+}
+
+bool IDATChunk::isValid() const
+{
+    return chunkId() == IDATChunk::defaultChunkId();
+}
+
+/*!
+ * Converts a YUV pixel to RGB.
+ */
+inline IPARChunk::Rgb yuvToRgb(IHDRChunk::Yuv yuv) {
+    IPARChunk::Rgb rgb;
+
+    // Green Book Cap. V Par. 4.4.2.2
+    const auto b = yuv.y + (yuv.u - 128.) * 1.733;
+    const auto r = yuv.y + (yuv.v - 128.) * 1.371;
+    const auto g = (yuv.y - 0.299 * r - 0.114 * b) / 0.587;
+
+    rgb.r = quint8(std::clamp(r + 0.5, 0., 255.));
+    rgb.g = quint8(std::clamp(g + 0.5, 0., 255.));
+    rgb.b = quint8(std::clamp(b + 0.5, 0., 255.));
+
+    return rgb;
+}
+
+
+QByteArray IDATChunk::strideRead(QIODevice *d, qint32 y, const IHDRChunk *header, const IPARChunk *params) const
+{
+    Q_UNUSED(y)
+    Q_UNUSED(params)
+    if (!isValid() || header == nullptr || d == nullptr) {
+        return {};
+    }
+
+    auto read = strideSize(header);
+    for (auto nextPos = nextChunkPos(); !d->atEnd() && d->pos() < nextPos;) {
+        auto rr = d->read(read);
+
+        if (header->model() == IHDRChunk::CLut4) {
+            if (rr.size() < header->width() / 2) {
+                return {};
+            }
+            QByteArray tmp(header->width(), char());
+            for (auto x = 0, w = header->width(); x < w; ++x) {
+                auto i8 = quint8(rr.at(x / 2));
+                tmp[x] = x & 1 ? i8 & 0xF : (i8 >> 4) & 0xF;
+            }
+            rr = tmp;
+        }
+
+        if (header->model() == IHDRChunk::Rgb555) {
+            for(qint32 x = 0, w = rr.size() - 1; x < w; x += 2) {
+                std::swap(rr[x], rr[x + 1]);
+            }
+        }
+
+        if (header->model() == IHDRChunk::DYuv) {
+            if (rr.size() < header->width()) {
+                return {};
+            }
+
+            // delta table: Green Book Cap. V Par. 3.4.1.3
+            // NOTE 1: using the wrong delta table creates visible artifacts on the image.
+            // NOTE 2: using { 0, 1, 4, 9, 16, 27, 44, 79, -128, -79, -44, -27, -16, -9, -4, -1 }
+            //         table gives the same result (when assigned to an uint8).
+            static const qint32 deltaTable[16] = {
+                0, 1, 4, 9, 16, 27, 44, 79, 128, 177, 212, 229, 240, 247, 252, 255
+            };
+
+            auto yuv = header->yuvStart();
+            QByteArray tmp(header->width() * 3, char());
+            for (auto x = 0, w = header->width() - 1; x < w; x += 2) {
+                // nibble order from Green Book Cap. V Par. 6.5.1.1
+                // NOTE: using the wrong nibble order creates visible artifacts on the image.
+                const auto du = deltaTable[(rr.at(x) >> 4) & 0x0F];
+                const auto d1 = deltaTable[rr.at(x) & 0x0F];
+                const auto dv = deltaTable[(rr.at(x + 1) >> 4) & 0x0F];
+                const auto d2 = deltaTable[rr.at(x + 1) & 0x0F];
+
+                // pixel 1
+                yuv.y = d1 + yuv.y;
+                yuv.u = du + yuv.u;
+                yuv.v = dv + yuv.v;
+                auto rgb = yuvToRgb(yuv);
+                tmp[x * 3] = rgb.r;
+                tmp[x * 3 + 1] = rgb.g;
+                tmp[x * 3 + 2] = rgb.b;
+
+                // pixel 2
+                yuv.y = d2 + yuv.y;
+                rgb = yuvToRgb(yuv);
+                tmp[(x + 1) * 3] = rgb.r;
+                tmp[(x + 1) * 3 + 1] = rgb.g;
+                tmp[(x + 1) * 3 + 2] = rgb.b;
+            }
+            rr = tmp;
+        }
+
+        return rr;
+    }
+
+    return {};
+}
+
+bool IDATChunk::resetStrideRead(QIODevice *d) const
+{
+    return seek(d);
+}
+
+quint32 IDATChunk::strideSize(const IHDRChunk *header) const
+{
+    if (header == nullptr) {
+        return 0;
+    }
+
+    auto rs = (header->width() * header->depth() + 7) / 8;
+
+    // No padding bytes are inserted in the data.
+    if (header->model() == IHDRChunk::Rgb888) {
+        return rs;
+    }
+
+    // The first pixel of each scan line must begin in a longword boundary.
+    if (auto mod = rs % 4)
+        rs += (4 - mod);
+    return rs;
+}
+
+
 /* ******************
  * *** BEAM Chunk ***
  * ****************** */

src/imageformats/chunks_p.h

@@ -55,6 +55,10 @@ Q_DECLARE_LOGGING_CATEGORY(LOG_IFFPLUGIN)
 #define CMAP_CHUNK QByteArray("CMAP")
 #define CMYK_CHUNK QByteArray("CMYK") // https://wiki.amigaos.net/wiki/ILBM_IFF_Interleaved_Bitmap#ILBM.CMYK
 #define DPI__CHUNK QByteArray("DPI ")
+#define IDAT_CHUNK QByteArray("IDAT")
+#define IHDR_CHUNK QByteArray("IHDR")
+#define IPAR_CHUNK QByteArray("IPAR")
+#define PLTE_CHUNK QByteArray("PLTE")
 #define XBMI_CHUNK QByteArray("XBMI")
 
 // Different palette for scanline
@@ -82,11 +86,13 @@ Q_DECLARE_LOGGING_CATEGORY(LOG_IFFPLUGIN)
 #define VERS_CHUNK QByteArray("VERS")
 #define XMP0_CHUNK QByteArray("XMP0") // https://aminet.net/package/docs/misc/IFF-metadata
 
+// FORM types
 #define ACBM_FORM_TYPE QByteArray("ACBM")
 #define ILBM_FORM_TYPE QByteArray("ILBM")
 #define PBM__FORM_TYPE QByteArray("PBM ")
 #define RGB8_FORM_TYPE QByteArray("RGB8")
 #define RGBN_FORM_TYPE QByteArray("RGBN")
+#define IMAG_FORM_TYPE QByteArray("IMAG")
 
 #define CIMG_FOR4_TYPE QByteArray("CIMG")
 #define TBMP_FOR4_TYPE QByteArray("TBMP")
@@ -756,10 +762,11 @@ public:
     /*!
      * \brief readStride
      * \param d The device.
-     * \param header The bitmap header.
      * \param y The current scanline.
+     * \param header The bitmap header.
      * \param camg The CAMG chunk (optional)
      * \param cmap The CMAP chunk (optional)
+     * \param ipal The per-line palette chunk (optional)
      * \param formType The type of the current form chunk.
      * \return The scanline as requested for QImage.
      * \warning Call resetStrideRead() once before this one.
@@ -776,8 +783,6 @@ public:
      * \brief resetStrideRead
      * Reset the stride read set the position at the beginning of the data and reset all buffers.
      * \param d The device.
-     * \param header The BMHDChunk chunk (mandatory)
-     * \param camg The CAMG chunk (optional)
      * \return True on success, otherwise false.
      * \sa strideRead
      * \note Must be called once before strideRead().
@@ -788,6 +793,7 @@ public:
      * \brief safeModeId
      * \param header The header.
      * \param camg The CAMG chunk.
+     * \param cmap The CMAP chunk.
      * \return The most likely ModeId if not explicitly specified.
      */
     static CAMGChunk::ModeIds safeModeId(const BMHDChunk *header, const CAMGChunk *camg, const CMAPChunk *cmap = nullptr);
@@ -921,6 +927,11 @@ public:
 
 protected:
     virtual bool innerReadStructure(QIODevice *d) override;
+
+private:
+    QImage::Format iffFormat() const;
+
+    QImage::Format cdiFormat() const;
 };
 
 
@@ -1400,6 +1411,267 @@ protected:
     virtual bool innerReadStructure(QIODevice *d) override;
 };
 
+/*!
+ * *** I-CD IFF CHUNKS ***
+ */
+
+/*!
+ * \brief The IHDRChunk class
+ * Image Header
+ */
+class IHDRChunk: public IFFChunk
+{
+public:
+    enum Model {
+        Invalid = 0, /**< Invalid model. */
+        Rgb888 = 1, /**< red, green, blue - 8 bits per color. */
+        Rgb555 = 2, /**< Green Book absolute RGB. */
+        DYuv = 3, /**< Green Book Delta YUV. */
+        CLut8 = 4, /**< Green Book 8 bit CLUT. */
+        CLut7 = 5, /**< Green Book 7 bit CLUT. */
+        CLut4 = 6, /**< Green Book 4 bit CLUT. */
+        CLut3 = 7, /**< Green Book 3 bit CLUT. */
+        Rle7 = 8, /**< Green Book runlength coded 7 bit CLUT. */
+        Rle3 = 9, /**< Green Book runlength coded 3 bit CLUT. */
+        PaletteOnly = 10 /**< color palette only. */
+    };
+
+    enum DYuvKind {
+        One = 0,
+        Each = 1
+    };
+
+    struct Yuv {
+        Yuv(quint8 y0 = 0, quint8 u0 = 0, quint8 v0 = 0) : y(y0), u(u0), v(v0) {}
+        quint8 y;
+        quint8 u;
+        quint8 v;
+    };
+
+    virtual ~IHDRChunk() override;
+
+    IHDRChunk();
+    IHDRChunk(const IHDRChunk& other) = default;
+    IHDRChunk& operator =(const IHDRChunk& other) = default;
+
+    virtual bool isValid() const override;
+
+    /*!
+     * \brief width
+     * \return Width of the bitmap in pixels.
+     */
+    qint32 width() const;
+
+    /*!
+     * \brief height
+     * \return Height of the bitmap in pixels.
+     */
+    qint32 height() const;
+
+    /*!
+     * \brief size
+     * \return Size in pixels.
+     */
+    QSize size() const;
+
+    /*!
+     * \brief lineSize
+     * Physical width of image (number of bytes in each scan line, including any data required at
+     * the end of each scan line for padding [see description of each model’s IDAT chunk for padding
+     * rules]) This field is not used when model() = Rle7 or Rle3.
+     * When model() = Rgb555, this field defines the size of one scan line of the upper
+     * or lower portion of the pixel data, but not the size of them both together.
+     */
+    qint32 lineSize() const;
+
+    /*!
+     * \brief model
+     * Image model (coding method)
+     */
+    Model model() const;
+
+    /*!
+     * \brief depth
+     * Physical size of pixel (number of bits per pixel used in storing image data) When
+     * model() = Rle7 or Rle3, this value only represents the size of a
+     * single pixel; the size of a run of pixels is indeterminate.
+     */
+    quint16 depth() const;
+
+    /*!
+     * \brief yuvKind
+     * if model() = DYuv, indicates whether there is one DYUV start value for all
+     * scan lines (in yuvStart()), or whether each scan line has its own start value in the
+     * YUVS chunk which follows.
+     */
+    DYuvKind yuvKind() const;
+
+    /*!
+     * \brief yuvStart
+     * Start values for DYUV image if model() = DYuv and dYuvKind() = One
+     */
+    Yuv yuvStart() const;
+
+    CHUNKID_DEFINE(IHDR_CHUNK)
+
+protected:
+    virtual bool innerReadStructure(QIODevice *d) override;
+};
+
+
+/*!
+ * \brief The IHDRChunk class
+ */
+class IPARChunk: public IFFChunk
+{
+public:
+    struct Rgb {
+        Rgb(quint8 r0 = 0, quint8 g0 = 0, quint8 b0 = 0) : r(r0), g(g0), b(b0) {}
+        quint8 r;
+        quint8 g;
+        quint8 b;
+    };
+
+    virtual ~IPARChunk() override;
+
+    IPARChunk();
+    IPARChunk(const IPARChunk& other) = default;
+    IPARChunk& operator =(const IPARChunk& other) = default;
+
+    virtual bool isValid() const override;
+
+    /*!
+     * \brief xOffset
+     * X offset of origin in source image [0 < xOffset() < xPage()]
+     */
+    qint32 xOffset() const;
+
+    /*!
+     * \brief yOffset
+     * \returnX offset of origin in source image [0 < yOffset() < yPage()]
+     */
+    qint32 yOffset() const;
+
+    /*!
+     * \brief aspectRatio
+     * Aspect ratio of pixels in source image.
+     */
+    double aspectRatio() const;
+
+    /*!
+     * \brief xPage
+     * X size of source image.
+     */
+    qint32 xPage() const;
+
+    /*!
+     * \brief yPage
+     * Y size of source image.
+     */
+    qint32 yPage() const;
+
+    /*!
+     * \brief xGrub
+     * X location of hot spot within image.
+     */
+    qint32 xGrub() const;
+
+    /*!
+     * \brief yGrub
+     * Y location of hot spot within image.
+     */
+    qint32 yGrub() const;
+
+    /*!
+     * \brief transparency
+     * Transparent color.
+     */
+    Rgb transparency() const;
+
+    /*!
+     * \brief mask
+     * Mask color.
+     */
+    Rgb mask() const;
+
+    CHUNKID_DEFINE(IPAR_CHUNK)
+
+protected:
+    virtual bool innerReadStructure(QIODevice *d) override;
+};
+
+
+/*!
+ * \brief The PLTEChunk class
+ */
+class PLTEChunk : public CMAPChunk
+{
+public:
+    virtual ~PLTEChunk() override;
+    PLTEChunk();
+    PLTEChunk(const PLTEChunk& other) = default;
+    PLTEChunk& operator =(const PLTEChunk& other) = default;
+
+    virtual bool isValid() const override;
+
+    /*!
+     * \brief count
+     * \return The number of color in the palette.
+     */
+    virtual qint32 count() const override;
+
+    CHUNKID_DEFINE(PLTE_CHUNK)
+
+protected:
+    qint32 offset() const;
+
+    qint32 total() const;
+
+    virtual QList<QRgb> innerPalette() const override;
+};
+
+/*!
+ * \brief The IDATChunk class
+ */
+class IDATChunk : public IFFChunk
+{
+public:
+    virtual ~IDATChunk() override;
+    IDATChunk();
+    IDATChunk(const IDATChunk& other) = default;
+    IDATChunk& operator =(const IDATChunk& other) = default;
+
+    virtual bool isValid() const override;
+
+    CHUNKID_DEFINE(IDAT_CHUNK)
+
+    /*!
+     * \brief readStride
+     * \param d The device.
+     * \param y The current scanline.
+     * \param header The bitmap header.
+     * \param params The additional parameters (optional)
+     * \return The scanline as requested for QImage.
+     * \warning Call resetStrideRead() once before this one.
+     */
+    QByteArray strideRead(QIODevice *d,
+                          qint32 y,
+                          const IHDRChunk *header,
+                          const IPARChunk *params = nullptr) const;
+
+    /*!
+     * \brief resetStrideRead
+     * Reset the stride read set the position at the beginning of the data and reset all buffers.
+     * \param d The device.
+     * \return True on success, otherwise false.
+     * \sa strideRead
+     * \note Must be called once before strideRead().
+     */
+    bool resetStrideRead(QIODevice *d) const;
+
+protected:
+    quint32 strideSize(const IHDRChunk *header) const;
+};
 
 /*!
  * *** UNDOCUMENTED CHUNKS ***

src/imageformats/iff.cpp

@@ -262,14 +262,21 @@ static void addMetadata(QImage &img, const IFOR_Chunk *form)
 
     // if no explicit resolution was found, apply the aspect ratio to the default one
     if (!resChanged) {
-        auto headers = IFFChunk::searchT<BMHDChunk>(form);
-        if (!headers.isEmpty()) {
-            auto xr = headers.first()->xAspectRatio();
-            auto yr = headers.first()->yAspectRatio();
-            if (xr > 0 && yr > 0 && xr > yr) {
-                img.setDotsPerMeterX(img.dotsPerMeterX() * yr / xr);
-            } else if (xr > 0 && yr > 0 && xr < yr) {
-                img.setDotsPerMeterY(img.dotsPerMeterY() * xr / yr);
+        if (form->formType() == IMAG_FORM_TYPE) {
+            auto params = IFFChunk::searchT<IPARChunk>(form);
+            if (!params.isEmpty()) {
+                img.setDotsPerMeterY(img.dotsPerMeterY() * params.first()->aspectRatio());
+            }
+        } else {
+            auto headers = IFFChunk::searchT<BMHDChunk>(form);
+            if (!headers.isEmpty()) {
+                auto xr = headers.first()->xAspectRatio();
+                auto yr = headers.first()->yAspectRatio();
+                if (xr > 0 && yr > 0 && xr > yr) {
+                    img.setDotsPerMeterX(img.dotsPerMeterX() * yr / xr);
+                } else if (xr > 0 && yr > 0 && xr < yr) {
+                    img.setDotsPerMeterY(img.dotsPerMeterY() * xr / yr);
+                }
             }
         }
     }
@@ -475,6 +482,67 @@ bool IFFHandler::readMayaImage(QImage *image)
     return true;
 }
 
+bool IFFHandler::readCDIImage(QImage *image)
+{
+    auto forms = d->searchForms<FORMChunk>();
+    if (forms.isEmpty()) {
+        return false;
+    }
+    auto cin = qBound(0, currentImageNumber(), int(forms.size() - 1));
+    auto &&form = forms.at(cin);
+
+    // show the first one (I don't have a sample with many images)
+    auto headers = IFFChunk::searchT<IHDRChunk>(form);
+    if (headers.isEmpty()) {
+        qCWarning(LOG_IFFPLUGIN) << "IFFHandler::readCDIImage(): no supported image found";
+        return false;
+    }
+
+    // create the image
+    auto &&header = headers.first();
+    auto img = imageAlloc(header->size(), form->format());
+    if (img.isNull()) {
+        qCWarning(LOG_IFFPLUGIN) << "IFFHandler::readCDIImage(): error while allocating the image";
+        return false;
+    }
+
+    // set the palette
+    if (img.format() == QImage::Format_Indexed8) {
+        auto pltes = IFFChunk::searchT<PLTEChunk>(form);
+        if (!pltes.isEmpty()) {
+            img.setColorTable(pltes.first()->palette());
+        }
+    }
+
+    // decoding the image
+    auto bodies = IFFChunk::searchT<IDATChunk>(form);
+    if (bodies.isEmpty()) {
+        img.fill(0);
+    } else {
+        auto &&body = bodies.first();
+        if (!body->resetStrideRead(device())) {
+            qCWarning(LOG_IFFPLUGIN) << "IFFHandler::readCDIImage(): error while reading image data";
+            return false;
+        }
+        auto pars = IFFChunk::searchT<IPARChunk>(form);
+        for (auto y = 0, h = img.height(); y < h; ++y) {
+            auto line = reinterpret_cast<char*>(img.scanLine(y));
+            auto ba = body->strideRead(device(), y, header, pars.isEmpty() ? nullptr : pars.first());
+            if (ba.isEmpty()) {
+                qCWarning(LOG_IFFPLUGIN) << "IFFHandler::readCDIImage(): error while reading image scanline";
+                return false;
+            }
+            memcpy(line, ba.constData(), std::min(img.bytesPerLine(), ba.size()));
+        }
+    }
+
+    // set metadata (including image resolution)
+    addMetadata(img, form);
+
+    *image = img;
+    return true;
+}
+
 bool IFFHandler::read(QImage *image)
 {
     if (!d->readStructure(device())) {
@@ -490,6 +558,10 @@ bool IFFHandler::read(QImage *image)
         return true;
     }
 
+    if (readCDIImage(image)) {
+        return true;
+    }
+
     qCWarning(LOG_IFFPLUGIN) << "IFFHandler::read(): no supported image found";
     return false;
 }

src/imageformats/iff_p.h

@@ -35,6 +35,8 @@ private:
 
     bool readMayaImage(QImage *image);
 
+    bool readCDIImage(QImage *image);
+
 private:
     const QScopedPointer<IFFHandlerPrivate> d;
 };