Auto exposure messes up preview / histrogram
- Enable Exposure module
- Enable Auto
The preview of the image (top-left corner) turns white, and the histrogram (top-right corner) gets messed up values.
Adjust the Exposure slider and the preview / histrogram turns normal again.
darktable 1.0.5+12~g3c330a7 (latest stable branch)
partial fix for bug #8905
still to be solved: preview window and histogram are lagging behind
center view when autoexposure area is changed
Revert "partial fix for bug #8905"
This reverts commit 0f63fb419ae19a9a80e69d4f97bd89cd4463d36c.
Was a bad idea that would lead to instable UI
#2 Updated by Ulrich Pegelow about 7 years ago
- % Done changed from 0 to 10
- Target version set to Candidate for next major release
- Assignee set to Ulrich Pegelow
- Status changed from New to Confirmed
Confirmed. Also affects current master.
Reason seems to be a wrong interpretation of the rectangular selection window on which auto exposure relies.
#3 Updated by Ulrich Pegelow about 7 years ago
Unfortunately the underlying problem is more complicated than thought.
It seems to be linked to the inner synchronization between center view, preview and color picker.
I hope that someone with a deep understanding of that synchronization can help (maybe hanatos, if he
finds some time)
This is what happens, when autoexposure is pressed:
- the module is flagged that it wants to collect color picker data (color picker
data are collected from the preview window)
- at first no data is valid (all are zero)
- module exposure takes these values and translates them into a very high positive EV correction
- shortly the image gets white (high positive EV)
- as the image is reprocessed due to change of EV value, also color picker data are resampled and valid now
- valid (changed) color picker data are seen by module exposure and cause reprocessing, now with reasonable results
- center view is adjusted accordingly
- for some reason, unknown to me, preview window and thus histogram lags behind, it still shows the previous white
picture with wrong EV compensation; this lagging behind also happens frequently when you manually change the rectangular
selection and seems to be a general problem with synchronization between the two
#5 Updated by Ulrich Pegelow about 7 years ago
- % Done changed from 10 to 50
- Priority changed from High to Medium
- Status changed from Confirmed to In Progress
I just pushed a partial fix into git master.
At least at first activation of autoexposure the preview window and histogram are now
correctly displayed. Still, due to the lagging behind of preview window, differences
will arise if color picker selection area is changed. Intermediate remedy: when selecting
a new rectangular area wait some moment before releasing mouse button.