Autocontrast can fail on a single black pixel

Bug #424641 reported by Stani on 2009-09-05
This bug affects 1 person
Affects Status Importance Assigned to Milestone

Bug Description

(02:12:36) ideasman_42: stani, did you write phatch ?
(02:15:47) stani: ideasman_42: yes, I am actually writing it
(02:16:14) ideasman_42: stani, ah, my dad was using it for a bit, but we had some trouble with the brightness contrast
(02:16:35) ideasman_42: hes making a book and needed to make a whole lot of gray scans more contrasting
(02:17:06) stani: ideasman_42: did autocontrast work?
(02:17:19) ideasman_42: the problem was there seemed to be no way to make gray tones black without 100% contrast
(02:17:36) ideasman_42: didnt try but wanted all the scans to have the same color adjustment
(02:18:25) ideasman_42: stani, we did a lot of trial and error on this
(02:18:45) ideasman_42: and Im fairly sure the way it does contrast is odd or at least different to most other apps
(02:18:53) ideasman_42: stani, what would be awesome would be simple levels
(02:19:22) ideasman_42: since we only wanted to make the greys black and leave the white alone
(02:25:06) stani: ideasman_42, send me such a picture or give a download link, i like real world test cases
(02:25:09) ideasman_42: stani, , wanted something like this
(02:25:16) stani: ok
(02:26:00) ideasman_42: but in a pradictable way- the problem with auto is if you apply to every picture, a small black pixel can throw it off
(02:26:57) stani: ideasman_42: would you mind if i attach these images to a bug report?
(02:27:08) ideasman_42: stani, np
(02:27:12) stani: ideasman_42, as your fathers contact details are on it
(02:27:21) ideasman_42: nah its ifne
(02:27:23) ideasman_42: fine*
(02:27:33) ideasman_42: the books online anyway
(02:28:10) ideasman_42: stani, had to use xnview instead, good ol Motif interface :S
(02:29:44) stani: which command in xnview?
(02:30:23) ideasman_42: contrast of 20 and "Change Gammut" of 0.5
(02:30:56) stani: that should be in imagemagick
(02:31:09) mp3man4: ideasman_42: does the documentation update reflect the status in python in most recent graphical builds? or is it being updated and changed?
(02:31:25) ideasman_42: stani, still, what do you think about levels in phatch, not as some external option?
(02:32:03) stani: ideasman_42: i think it is fine, but what do you mean as an external option?
(02:32:21) ideasman_42: stani, I meant as a built in filter thats easy to access
(02:32:23) ideasman_42: hey papo
(02:32:45) ideasman_42: like contrast is now, if internally it uses some other method then thats fine
(02:33:09) ideasman_42: could be 2 sliders, black levels and white levels if you didnt want to make an interface like the gimp

Stani (stani) wrote :

Source file

Changed in phatch:
importance: Undecided → Low
status: New → Confirmed
Stani (stani) wrote :

Desired outcome

Stani (stani) on 2009-09-05
description: updated
Stani (stani) on 2009-09-05
Changed in phatch:
importance: Low → Wishlist
Stani (stani) wrote :

This will be fixed after the 0.2 release.

Changed in phatch:
status: Confirmed → Triaged
Stani (stani) on 2010-02-22
Changed in phatch:
assignee: nobody → Ed Cranford (ed-cranford)
Stani (stani) on 2010-02-23
Changed in phatch:
milestone: none → 0.2.7
status: Triaged → Confirmed
summary: - autocontrast can fail on a single black pixel
+ Autocontrast can fail on a single black pixel
Stani (stani) on 2010-02-28
Changed in phatch:
milestone: 0.2.7 → 0.2.8
Changed in phatch:
assignee: Ed Cranford (ed--cranford) → nobody
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