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JXL: Resolution and metadata support via EXIF
- Added a class to read and write minimal exif metadata.
- JXL plugin uses EXIF metadata to load/save the resolution of the image (like GIMP).
- JXL plugin uses EXIF metadata to set/store text metadata and date/time.
- Enable info display in Dolphin (JXL File -> Properties -> Details on a JXL file, see image below).
- Enabled read test to check also image metadata and resolution.
{width=401 height=357}
This commit is contained in:
Mirco Miranda
157
README.md
157
README.md
@ -113,17 +113,89 @@ clamp). This is not a plugin issue.
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### Metadata
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Metadata support is implemented in all formats that support it. In particular,
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in addition to the classic `"Description"`, `"Author"`, `"Copyright"`, etc... where
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possible, XMP data is supported via the `"XML:com.adobe.xmp"` key.
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Metadata support is available in formats that include it via
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`QImage::setText()` and `QImage::text()`. To ensure consistent metadata
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functionality, the following keys have been adopted.
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Please note that only the most common metadata is supported.
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About the image:
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- `Altitude`: Floating-point number indicating the GPS altitude in meters
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above sea level (e.g. 35.4).
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- `Author`: Person who created the image.
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- `Comment`: Additional image information in human-readable form, for
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example a verbal description of the image.
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- `Copyright`: Copyright notice of the person or organization that claims
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the copyright to the image.
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- `CreationDate`: Creation date and time in ISO 8601 format without
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milliseconds (e.g. 2024-03-23T15:30:43).
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- `Description`: A string that describes the subject of the image.
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- `DocumentName`: The name of the document from which this image was
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scanned.
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- `HostComputer`: The computer and/or operating system in use at the time
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of image creation.
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- `Latitude`: Floating-point number indicating the latitude in degrees
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north of the equator (e.g. 27.717).
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- `Longitude`: Floating-point number indicating the longitude in degrees
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east of Greenwich (e.g. 85.317).
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- `Owner`: Name of the owner of the image.
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- `Software`: Name and version number of the software package(s) used to
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create the image.
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- `Title`: The title of the image.
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About the camera:
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- `Manufacturer`: The manufacturer of the recording equipment.
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- `Model`: The model name or model number of the recording equipment.
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- `SerialNumber`: The serial number of the recording equipment.
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About the lens:
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- `LensManufacturer`: The manufacturer of the interchangeable lens that was
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used.
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- `LensModel`: The model name or model number of the lens that was used.
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- `LensSerialNumber`: The serial number of the interchangeable lens that was
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used.
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Complex metadata (requires a parser):
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- `XML:org.gimp.xml`: XML metadata generated by GIMP and present only in XCF
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files.
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- `XML:com.adobe.xmp`: [Extensible Metadata Platform (XMP)](https://developer.adobe.com/xmp/docs/)
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is the metadata standard used by Adobe applications and is supported by all
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common image formats. **Note that XMP metadata is read and written by
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plugins as is.** Since it may contain information present in other metadata
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(e.g. `Description`), it is the user's responsibility to ensure consistency
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between all metadata and XMP metadata when writing an image.
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Supported metadata may vary from one plugin to another. Please note that only
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the most common metadata are supported and some plugins may return keys not
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listed here.
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### EXIF Metadata
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[EXIF (Exchangeable Image File Format)](https://en.wikipedia.org/wiki/Exif)
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metadata is a standard for embedding information within the image file itself.
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Unlike the metadata described above, EXIF metadata is used internally by some
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plugins to standardize image handling. For example, the JXL plugin uses them
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to **set/get the image resolution and metadata**. They are also needed to
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make the image properties appear in the file details of some file managers
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(e.g. Dolphin).
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When reading, EXIF metadata is converted into simple metadata (e.g.
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`Description`) and inserted into the image if and only if it is not already
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present.
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On writing, the image metadata is converted to EXIF and saved appropriately.
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Note that, if not present in the image to be saved, the following metadata
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are created automatically:
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- `Software`: Created using `applicationName` and `applicationVersion` methods
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of [`QCoreApplication`](https://doc.qt.io/qt-6/qcoreapplication.html).
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- `CreationDate`: Set to current time and date.
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### ICC profile support
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ICC support is fully implemented in all formats that support it. When saving,
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some formats convert the image using color profiles according to
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specifications. In particular, HDR formats almost always convert to linear
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ICC profile support is implemented in all formats that handle them using
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[`QColorSpace`](https://doc.qt.io/qt-6/qcolorspace.html). When saving, some
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plugins convert the image using color profiles according to format
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specifications. In particular, HDR formats almost always convert to linear
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RGB.
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### Maximum image size
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@ -194,8 +266,10 @@ compiled with Qt 6.8+.
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**This plugin can be disabled by setting `KIMAGEFORMATS_DDS` to `OFF`
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in your cmake options.**
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The following defines can be defined in cmake to modify the behavior of the plugin:
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- `DDS_DISABLE_STRIDE_ALIGNMENT`: disable the stride aligment based on DDS pitch: it is known that some writers do not set it correctly.
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The following defines can be defined in cmake to modify the behavior of the
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plugin:
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- `DDS_DISABLE_STRIDE_ALIGNMENT`: disable the stride aligment based on DDS
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pitch: it is known that some writers do not set it correctly.
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### The HEIF plugin
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@ -209,9 +283,13 @@ will compile but will fail the tests.
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### The EXR plugin
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The following defines can be defined in cmake to modify the behavior of the plugin:
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- `EXR_CONVERT_TO_SRGB`: the linear data is converted to sRGB on read to accommodate programs that do not support color profiles.
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- `EXR_DISABLE_XMP_ATTRIBUTE`: disables the stores XMP values in a non-standard attribute named "xmp". Note that Gimp reads the "xmp" attribute and Darktable writes it as well.
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The following defines can be defined in cmake to modify the behavior of the
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plugin:
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- `EXR_CONVERT_TO_SRGB`: the linear data is converted to sRGB on read to
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accommodate programs that do not support color profiles.
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- `EXR_DISABLE_XMP_ATTRIBUTE`: disables the stores XMP values in a non-standard
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attribute named "xmp". Note that Gimp reads the "xmp" attribute and Darktable
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writes it as well.
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### The EPS plugin
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@ -223,8 +301,10 @@ create a temporary PDF file which is then converted to EPS. Therefore, if
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### The HDR plugin
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The following defines can be defined in cmake to modify the behavior of the plugin:
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- `HDR_HALF_QUALITY`: on read, a 16-bit float image is returned instead of a 32-bit float one.
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The following defines can be defined in cmake to modify the behavior of the
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plugin:
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- `HDR_HALF_QUALITY`: on read, a 16-bit float image is returned instead of a
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32-bit float one.
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### The JP2 plugin
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@ -232,16 +312,19 @@ The following defines can be defined in cmake to modify the behavior of the plug
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in your cmake options.**
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JP2 plugin has the following limitations due to the lack of support by OpenJPEG:
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- Metadata are not supported
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- Image resolution is not supported
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- Metadata are not supported.
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- Image resolution is not supported.
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### The JXL plugin
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**The current version of the plugin limits the image size to 256 megapixels
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according to feature level 5 of the JXL stream encoding.**
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The following defines can be defined in cmake to modify the behavior of the plugin:
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- `JXL_HDR_PRESERVATION_DISABLED`: disable floating point images (both read and write) by converting them to UINT16 images. Any HDR data is lost. Note that FP images are always disabled when compiling with libJXL less than v0.9.
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The following defines can be defined in cmake to modify the behavior of the
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plugin:
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- `JXL_HDR_PRESERVATION_DISABLED`: disable floating point images (both read
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and write) by converting them to UINT16 images. Any HDR data is lost. Note
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that FP images are always disabled when compiling with libJXL less than v0.9.
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- `JXL_DECODE_BOXES_DISABLED`: disable reading of metadata (e.g. XMP).
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### The JXR plugin
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@ -249,11 +332,21 @@ The following defines can be defined in cmake to modify the behavior of the plug
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**This plugin is disabled by default. It can be enabled by settings
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`KIMAGEFORMATS_JXR` to `ON` in your cmake options.**
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The following defines can be defined in cmake to modify the behavior of the plugin:
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- `JXR_DENY_FLOAT_IMAGE`: disables the use of float images and consequently any HDR data will be lost.
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- `JXR_DISABLE_DEPTH_CONVERSION`: remove the neeeds of additional memory by disabling the conversion between different color depths (e.g. RGBA64bpp to RGBA32bpp) at the cost of reduced compatibility.
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- `JXR_DISABLE_BGRA_HACK`: Windows displays and opens JXR files correctly out of the box. Unfortunately it doesn't seem to open (P)RGBA @32bpp files as it only wants (P)BGRA32bpp files (a format not supported by Qt). Only for this format an hack is activated to guarantee total compatibility of the plugin with Windows.
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- `JXR_ENABLE_ADVANCED_METADATA`: enable metadata support (e.g. XMP). Some distributions use an incomplete JXR library that does not allow reading metadata, causing compilation errors.
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The following defines can be defined in cmake to modify the behavior of the
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plugin:
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- `JXR_DENY_FLOAT_IMAGE`: disables the use of float images and consequently
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any HDR data will be lost.
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- `JXR_DISABLE_DEPTH_CONVERSION`: remove the neeeds of additional memory by
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disabling the conversion between different color depths (e.g. RGBA64bpp to
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RGBA32bpp) at the cost of reduced compatibility.
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- `JXR_DISABLE_BGRA_HACK`: Windows displays and opens JXR files correctly out
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of the box. Unfortunately it doesn't seem to open (P)RGBA @32bpp files as
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it only wants (P)BGRA32bpp files (a format not supported by Qt). Only for
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this format an hack is activated to guarantee total compatibility of the
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plugin with Windows.
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- `JXR_ENABLE_ADVANCED_METADATA`: enable metadata support (e.g. XMP). Some
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distributions use an incomplete JXR library that does not allow reading
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metadata, causing compilation errors.
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### The KRA plugin
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@ -270,15 +363,19 @@ image.
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### The PSD plugin
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PSD support has the following limitations:
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- Only images saved by Photoshop using compatibility mode enabled (Photoshop default) can be decoded.
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- Only images saved by Photoshop using compatibility mode enabled (Photoshop
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default) can be decoded.
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- Multichannel images are treated as CMYK if they have 2 or more channels.
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- Multichannel images are treated as Grayscale if they have 1 channel.
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- Duotone images are treated as grayscale images.
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- Extra channels other than alpha are discarded.
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The following defines can be defined in cmake to modify the behavior of the plugin:
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- `PSD_FAST_LAB_CONVERSION`: the LAB image is converted to linear sRGB instead of sRGB which significantly increases performance.
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- `PSD_NATIVE_CMYK_SUPPORT_DISABLED`: disable native support for CMYK images when compiled with Qt 6.8+
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The following defines can be defined in cmake to modify the behavior of the
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plugin:
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- `PSD_FAST_LAB_CONVERSION`: the LAB image is converted to linear sRGB instead
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of sRGB which significantly increases performance.
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- `PSD_NATIVE_CMYK_SUPPORT_DISABLED`: disable native support for CMYK images
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when compiled with Qt 6.8+
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### The RAW plugin
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@ -293,7 +390,9 @@ The default setting tries to balance quality and conversion speed.
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### The XCF plugin
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XCF support has the following limitations:
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- XCF format up to [version 12](https://testing.developer.gimp.org/core/standards/xcf/#version-history) (no support for GIMP 3).
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- XCF format up to [version 12](https://testing.developer.gimp.org/core/standards/xcf/#version-history)
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(no support for GIMP 3).
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- The returned image is always 8-bit.
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- Cannot read zlib compressed files.
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- The rendered image may be slightly different (colors/transparencies) than in GIMP.
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- The rendered image may be slightly different (colors/transparencies) than
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in GIMP.
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