1) First thing, some questions on yourself. What's your name? What's your job?
I remember having followed a discussion on the Rawtherapee forums about adding support for adjustment layers. The conclusion was simple: it would imply rewriting a good portion of the processing pipeline. The current situation with Darktable is better, as it supports local editing through blending masks for most of the tools, however adjustment layers are not in the todo list of the developers.
Last but not least, they are both limited to single images. No way for example to combine two or more exposures in a single image with extended dynamic range.
So I decided to take a different approach: define my ideal photo editor, see what building blocks could be used as a starting point, and eventually incorporate code from both Rawtherapee and Darktable whenever possible, just to avoid re-inventing the wheel.
First of all, what could be the characteristics of an ideal photo editor? Here is my shopping list:
- allow the direct processing of RAW files
- be non-destructive
- provide a real-time preview of the current editing
- allow to combine multiple images
- support adjustment layers as well as layers grouping, to achieve complex effects
- allow local editing with grayscale blending masks
- allow the editing of rather large images (100 mega-pixels or more), without "killing" your machine
From there on, PhotoFlow has been entirely built on top of VIPS, re-using existing code whenever possible. For example, the RAW processing part is largely derived from Darktable (RAW decoding and color matrices) and RawTherapee (Amaze, LMMSE and IGV demosaicing algorithms).
Last but not least, PhotoFlow saves sidecars files in XML format, without modifying the initial image(s). The XML files simply "register" all the editing steps, which are then "replied" by PhotoFlow whenever the file is opened. As such, any aspect of an edit can be modified and tweaked without any limits.
To conclude, PhotoFlow might well replace both your favorite RAW converter and GIMP in your daily photo retouching work, so why not give it a chance?