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<p>Hi Sveinn</p>
<p>I tried your suggestion on one photo and think this is a good
solution which I will adopt and try and modify for my needs. I
attached a link to the original photo and one to the repair I did
using your method without any further attempts to tweak or improve
the photo. The recovered colours are a good start to retrieving
the colours in old slides I digitized.</p>
<p>Thank you </p>
<p>Errol<br>
</p>
<p>old photo</p>
<p><a class="moz-txt-link-freetext"
href="https://mega.nz/file/QxlEAIbI#gwt5Omb5cSa1-WPeDxVlTdtyoNkwZYdeUC9xVp9L6b4">https://mega.nz/file/QxlEAIbI#gwt5Omb5cSa1-WPeDxVlTdtyoNkwZYdeUC9xVp9L6b4</a>
<br>
<br>
</p>
<p>corrected photo<br>
</p>
<p><a class="moz-txt-link-freetext"
href="https://mega.nz/file/E4U3nYza#D0Q9wgxmbNb2j5ou2kg74ETedTwcGeQyAPFisSwdz8U">https://mega.nz/file/E4U3nYza#D0Q9wgxmbNb2j5ou2kg74ETedTwcGeQyAPFisSwdz8U</a></p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 19/05/2021 15:48, Errol Sapir wrote:<br>
</div>
<blockquote type="cite"
cite="mid:7fc498f6-20ab-3399-cb96-583f2c9bc3de@tzora.co.il">
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<p>Hi Sveinn</p>
<p>Thank you for your detailed explanation and link to the
technical explanation. If I understand your solution seems to be
in Gimp. I will try and apply some of your methods and see where
it takes me. My main aim is to get decent usable photos right
away with the option of further tweaking the better ones after
restoration. I will report back here results. Meanwhile if there
are any further suggestions I would appreciate them.</p>
<p>TIA</p>
<p>Errol<br>
</p>
<div class="moz-cite-prefix">On 17/05/2021 14:57, Sveinn í Felli
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:bad184cf-51d3-828c-2f2d-098c4529b387@fellsnet.is">Þann
12.5.2021 17:48, skrifaði Errol Sapir <br>
<blockquote type="cite">Hi Gilles <br>
<br>
The idea isn't to invert colour but to enhance colour. The
slides have faded and <br>
the original colours aren't alive. The link shows a photo that
has faded. <br>
<br>
Errol <br>
<br>
<a class="moz-txt-link-freetext"
href="https://mega.nz/file/QxlEAIbI#gwt5Omb5cSa1-WPeDxVlTdtyoNkwZYdeUC9xVp9L6b4"
moz-do-not-send="true">https://mega.nz/file/QxlEAIbI#gwt5Omb5cSa1-WPeDxVlTdtyoNkwZYdeUC9xVp9L6b4</a>
<br>
<br>
</blockquote>
<br>
Hi Errol, <br>
<br>
Scanning and repairing old slides can be a complex matter; it
depends on brands of film, on previous storage of the slides,
and on type of mount (what kind of frame they've been mounted
in), and possibly other factors too. <br>
<br>
I've repaired several slides similar to the one you shared,
guess this one is an AGFA-GEVAERT positive film, possibly a
FUJIFILM. Sometimes a generic automatic filter like "Equalize"
will do the trick; problem is that often a great deal of image
info will be lost. Other problem is that usually not all the
original photos were ever "correctly" exposed. <br>
Existential problem; do you want to be faithful to the original
images or just get decent usable photos right away? <br>
<br>
I searched the web thoroughly for info on how to do this with
FOSS-software; there are some scripts (mostly for GIMP) for
certain types of film of certain age (yes, the year of
production counts), but the majority of those doing such work
resort to using the commercial extensions available for
Photoshop. Those are sort of databases with measured decay of
various types of film, along with commands for corresponding
filters. <br>
<br>
Nevertheless I found a neat procedure for doing this in GIMP
(can't find the source right now); Take one of a batch similar
slides (from one shooting, one year or similar exposure),
demount it from the plastic frame (bad luck if it's glued into a
paper frame) and scan the whole area, including the perforated
strip on both sides, where normally there should be markings in
clear letters with the brand name and number of the image. <br>
<br>
In "Levels" histogram mode with the eyedropper-tool in "All
channels" section, change the white-point to a decent sample of
a letter on the strip (transparent = white), similarly take the
black-point from the surrounding black/opaque frame, then pick a
gray-point (where a gray area should be) from the image itself.
This way you're compensating for the "natural" decay of the
corresponding film (of a certain brand, certain age). You may
then have to fiddle with all the color-components separately to
further enhance colors. The most important is to save the result
as a preset, and then use that preset manually on each image
(with further enhancements like sharpening etc.) or use it on
several images with GIMP --headless on the command line. <br>
<br>
You could also use the values from this preset to make settings
for the BatchQueue Manager in Digikam or some script for
ImageMagick. <br>
<br>
But as stated above, this procedure only compensates for the
natural decay of the film itself, not the decoloration of the
image due to sunlight or overuse (number of passages in a
projector). <br>
<br>
For those who like the technical side of things: <a
class="moz-txt-link-rfc2396E"
href="http://www.lionhouse.plus.com/photorestore/Restore2.pdf"
moz-do-not-send="true"><http://www.lionhouse.plus.com/photorestore/Restore2.pdf></a>
<br>
<br>
Good luck, <br>
<br>
Just some thoughts - good luck restoring your slides, <br>
Sveinn í Felli <br>
<br>
<br>
<blockquote type="cite">On 12/05/2021 11:50, Gilles Caulier
wrote: <br>
<blockquote type="cite"> <br>
<br>
Le mer. 12 mai 2021 à 04:39, Errol Sapir <<a
class="moz-txt-link-abbreviated"
href="mailto:errol@tzora.co.il" moz-do-not-send="true">errol@tzora.co.il</a>
<a class="moz-txt-link-rfc2396E"
href="mailto:errol@tzora.co.il" moz-do-not-send="true"><mailto:errol@tzora.co.il></a>>
a écrit : <br>
<br>
Hi All <br>
<br>
I am now trying Manjaro KDE after many years of Kununtu.
Of course I am <br>
also planning to transfer (or redo) my Digikam from
Kubuntu to Manjaro. I <br>
have however a photo question that doesn't specifically
apply specifically <br>
to either of these programs. As I said in the subject I
hope it isn't OT <br>
but as it is photo connected and I hope Digikam can help
as well I would <br>
appreciate the help of anyone who can. If it is OT the
moderators can <br>
remove my post and I will understand. <br>
<br>
I am transferring all my slides (and eventually
negatives) to digital <br>
format. I am looking for a one-click solution (program)
that will restore <br>
colours back to normal. <br>
<br>
<br>
<br>
You want mean to invert color ? If yes, ImageMagick is your
friend, especially -negate option: <br>
<br>
<a class="moz-txt-link-freetext"
href="https://superuser.com/questions/1194468/invert-colors-with-imagemagick"
moz-do-not-send="true">https://superuser.com/questions/1194468/invert-colors-with-imagemagick</a>
<br>
<br>
This can be scripted of course to parse and process
automatically all files from your collection. And of course,
all can be done de facto under Linux from command line. <br>
<br>
Else, In digiKam, Invert Color tool from Batch Queue Manager
can be used. Create a new Queue, assign items to process,
configure the output options (path, file name, etc...),
assign Invert tool + the convert format if necessary, and...
you can take a coffee. <br>
<br>
Best <br>
<br>
Gilles Caulier <br>
<br>
</blockquote>
<br>
</blockquote>
<br>
</blockquote>
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