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126 rindas
5.6 KiB
126 rindas
5.6 KiB
* Using littlecms for professional colourmanagement.
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Profiles are applied to image data on import, paste, copy, display and
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printing to calibrate for particular ways in which image data can
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be presented or created. Profiles are associated with a certain
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color space and with a device class.
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* The following profiles are available in Chalk:
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Image profile The image profile is the default profile
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for the default color space for the layers
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in Chalk
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Layer profile Chalk images can have layers of different
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color spaces, so each layer can have a
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different profile, too.
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Display profile When converting the visible part of
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an image for displaying on the users monitor,
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a monitor calibration profile can be applied
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to adjust for display idiosyncrasies.
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Import profile On importing an image from disk that does
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not have a profile embedded (XXX: embedded
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profiles aren't recoginized yet), a screenshot
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or a scan, the import profile is attached
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to the image.
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Output profile On printing, a profile can be applied to the
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image to compensate for the printer
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idiosyncrasies. XXX: Printing doesn't work
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yet at all, and printing is big task that
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should be part of KDE. We should simply
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convert an image to a tiff file with embedded
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profile, and send that to a system printer.
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* At the following points we need to handle profiles:
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File import Chalk uses ImageMagick to import files.
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ImageMagick knows about embedded profiles and
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makes them available in memory. We need to
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hack our IM builder to convert the in-memory
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profile blob to a profile handle.
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File export Chalk uses ImageMagick to export files.
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Here we need to do the reverse trick; take
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a profile handle and get IM to save it with
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the file.
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Paste from clipboard Two cases: Chalk has placed a clip on the
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clipboard, or another application has placed
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a clip on the clipboard. Clips are wrapped
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in the KisClip class that can be created with
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a profile. That can be the profile of the
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image Chalk copied the clip from, or the
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copy profile set in the Settings, or none.
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An external clip is always RGB8 (for now, no
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doubt Qt will extend its clipboard once RGB16
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images or RGB half images become widespread),
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so in those cases we always need an RGB
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profile.
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Paste from external applications is handled by
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the constructor from KisPaintDevice,
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internally it might entail a mode conversion.
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Copy to clipboard If another application consumes a clip Chalk
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has put on the clipboard it can receive the
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data as-is, or with a profile applied.
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Paste is handled by KisPaintDevice::convertToQImage.
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Display on monitor For calibrated displays. This is handled
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by KisPaintDevice::convertToQImage()
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Image mode conversion A user can either choose to convert an
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existing layer or image to another color
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model/profile/bit depth or the conversion can
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happen automatically, for instance when
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painting when the color of a pixel is
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converted from KoColor to the color in the
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color model.
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This is handled by
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KisStrategyColorSpace:convertTo().
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File loading Chalk's own file format now has a field for
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the product name of a profile. We need also to
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be able to embed the entire profile into a
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Chalk file. That should be easy, since a Chalk
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file is just a zipfile.
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File saving When loading a Chalk file format image we
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should also be able to load embedded profiles.
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* Chalk should have a few extra features that are easy to implement
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once I a) know what they mean, technically and b) the foregoing is
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completed. These are:
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Softproofing Showing the image on the monitor with profiles
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for printing applied, too.
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Out-of-gamut warnign Colours that cannot be printed are shown in
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some hideous colour.
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Blackpoint compenstion No idea about this...
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8-bit image dither No idea.
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... lcms offers more stuff that I don't know
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anything about but which might be interesting.
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* External factors play a role. We need a free display calibration
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tool for X11, a printing system that takes this stuff into account
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and all the rest. That's not part of Chalk, but it needs to be done
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some time. XXX: Ask the KGamma developers about this?
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