Darktable 4.2.0

What's new in this version:

The Big Ones:
- The following is a summary of the main features added to darktable 4.2. Most of these features are described more fully in the user manual.
- New Sigmoid display transform module, which can be used in place of the filmic and base curve modules.
- Two new algorithms are provided in the highlight reconstruction module:"inpaint opposed" and "segmentation based". The "inpaint opposed" algorithm has proved to be very stable and provides good results in many images, so it replaces "clip highlights" as the new default algorithm.
- The pixelpipe used for image display in the darkroom view has been reworked so that it can be used elsewhere (darkroom view, second display window, duplicate manager, style preview, snapshot routine). This has allowed for code de-duplication as well as enhancement of many of these features see below).
- The second darkroom image window has now been enhanced to support both the focus peaking and ISO-12646 color assessment modes.
- The snapshot module has been entirely reworked so that, instead of using a fixed screen capture it now uses a dynamically generated view using the new pixelpipe functionality. This means that it can now be zoomed and panned with keyboard/mouse.
- The duplicate manager previously used a different pipe routine to calculate its previews (i.e. when long-pressing on a duplicate image thumbnail) which often meant that the displayed duplicates differed from the main darkroom view in subtle ways. Use of the new pipe routine now means that these previews will be identical to those produced during darkroom editing.
- It is now possible to preview the effect of a user-generated style on an image before applying it. Simply hover over the style name in either the lighttable styles module or the darkroom quick-access menu and a
- new tooltip will appear, showing the image with the style applied along with details of the modules that are included.
- Some cameras record lens correction information within the image EXIF metadata. The lens correction module has been enhanced so that it can extract this data and use it to correct lens distortions.
- darktable is now able to read and write JPEG XL images Processing and utility modules have been altered so that if a module is not entirely visible when expanded, it will be automatically scrolled until the entire UI is visible on screen.
- For users who currently use the "scroll to the top when expanded" preference setting to achieve this effect, this change may provide a better alternative.
- As part of this change, a new animation effect has been added when expanding/collapsing modules. The speed of the expand/collapse animation can be controlled via a preference setting preferences > miscellaneous > duration of ui transitions). Set this to zero to disable the animation.
- The pixelpipe caching functionality has been completely overhauled. More cachelines are used with an improved hit-rate while controlling the total amount of memory used, leading to a significantly faster interface.
- The slideshow has been rewritten for a better user experience.
- A small preview is displayed while the full image is computed to provide feedback to the user that something is being done in the background.
- A new drop-down menu has been added to the top filter bar to allow filters to be easily added and removed. Some range widgets have been removed from this list as they are not easily readable on the top bar.
- The UI of the range rating filter widget has been reworked for better readability. This revised widget is designed to be easier to use and more efficient.

Other Changes:
- Added support for manipulating shapes without using the mouse scroll-wheel for tablet users). The mask manager has been enhanced with a new collapsible section containing controls for changing shapes properties.
- It is also possible to change a property that is shared by a group of shapes.
- The circle and ellipse shapes have also been enhanced with new on-canvas controls to change the mask size and feathering.
- WebP read support has been added.
- Embedded ICC profiles are now supported in exported WebP files. Double-clicking on a notebook tab now resets all widgets within that tab. Regional date/time format is now supported in thumbnail tooltips.
- Lua commands are displayed in a widget's "action" tooltip.
- The SSE code path has been removed from the white balance and output color profile modules as compiler defaults now provide a similar speed.
- Added support for JFIF (JPEG File Interchange Format) file extension which is an extension of the JPEG standard).
- The preference to auto-apply a sharpening has been removed. For users who still require this functionality, it can be easily achieved with a user-generated auto-applied preset.
- Added support for updating existing pictures in Piwigo export.
- All white balance presets have been migrated to an external JSON file. This should not affect the module's operation.
- The preferences to set the layout of the "color balance module" and the colors of the "white balance" module have been removed from the global preferences dialog, as these controls are already available directly within the respective modules.
- Improved profile support for AVIF & EXR format. Also relax AVIF reader support by not requiring full compliance.
- The current collection image count is now shown in the top bar beside the image filters meaning that it is available even when the top hinter area is hidden.
- Attempt to obtain the color-space for PNG files from the cICP chunk. This was added in a recent revision of the PNG spec, so we take advantage of it, if present.
- Reading of 16-bit half float for the TIFF format is now undertaken using the Imath library.
- The format and storage parameters in the export module can now be mapped to shortcuts.
- Introduced balanced "OpenCL vs CPU" tiling. This makes it possible to use CPU tiling if there is not enough memory on the OpenCL card which would require a lot of tiles to be handled on the card). In the end, the large number of tiles plus the overlapping area would make the use of the OpenCL code path slower (or much slower) than handling the image without tiling on the CPU.
- In preview mode (when pressing Ctrl+w) the image information overlay display block is no longer shown by default. Moving the cursor within the top half of the preview image will cause the overlay to appear, and it will then disappear again after a brief period.
- Light patterns are set for Behringer b-control midi rotors BCR2000/BCF2000)
- Fixed reading of EXIF metadata when importing EXR files (if desired, existing files must be re-imported, as it is not possible to refresh metadata).
- Added support for scrolling through a module's presets using shortcuts. Panels now use "natural sizes" by default, meaning that their initial size adjusts according to screen resolution.
- The geo-tagging module now better supports narrow side-panels by wrapping rather than ellipsizing text
- More actions have been added to the main help screen (displayed by pressing the h key)
- The lensfun library is now a mandatory dependency. This ensures that all darktable builds correctly include the lens correction module.
- This also means that an edit made using this module won't be inadvertently lost due to missing build dependencies
- It is now possible to assign shortcuts to the "currently focused" processing module. This allows a common set of shortcuts to be created and reused in multiple modules simply by focusing that module. For example a single key shortcut applied to the "first slider" will affect the "exposure" slider when the exposure module is focused, and the "rotation" slider when the "rotate and perspective" module is focused. Similar functionality can be used to affect the "nth" slider, combobox, button or tab as well as the focused module itself.