Query and modify the history stack of the current darkroom image.
This module lists every change of state (activate/de-activate/move/change parameters) for all image processing modules that have been modified for the current image. You can select a point in the stack to return to that point in the development history of the image.
Caution: adjusting any module will cause all modules above the currently selected one to be discarded. It is easy to lose development work on an image in this way!
It is safe to quit the program, leave the darkroom mode, or switch to another image while having selected some earlier state in the history stack module. When returning to that image you will find the history stack panel in the state where you left it.
Hovering the mouse over an item in the history stack will show a tooltip with details of all changes that were made in that module compared to its previous or default state. This can help track down adjustments that were made unintentionally and have unintended effects.
Clicking “compress history stack” generates the shortest history stack that reproduces the current image. It causes all edits above the currently-selected step to be discarded. If any module appears multiple times in the remainder of the stack, these multiple appearances will be compressed into a single step in the history.
Clicking “compress history stack” while holding the Ctrl key truncates the history stack, but without compressing it i.e. it discards all modules above the currently selected one but leaves the remainder of the history stack unchanged.
Clicking the “reset parameters” button in the module header discards the entire history stack and reactivates any default modules. This can also be achieved by selecting the “original image” history item and clicking “compress history stack”.
The button to the right of the “compress history stack” button allows you to create a new style from the history stack of the current image, which can then be applied to other images. Use the first line of the popup dialog window to name your style and the second to add a searchable description. You will be prompted to choose which of the current history stack modules to include in the style.
Once created, styles can be managed and applied to other images with the lighttable’s styles module. You can also assign shortcut keys to your styles (see preferences > shortcuts) and apply the associated style to all selected images by pressing the shortcut key whenever you are in the lighttable or darkroom view.