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<p>Le 05/10/2025 à 13:00, <a
class="moz-txt-link-abbreviated moz-txt-link-freetext"
href="mailto:digikam-users-request@kde.org">digikam-users-request@kde.org</a>
a écrit :</p>
<div class="moz-cite-prefix"><span style="white-space: pre-wrap">
</span><span style="white-space: pre-wrap">
</span></div>
<blockquote type="cite"
cite="mid:mailman.17.1759662001.3787.digikam-users@kde.org">
<pre wrap="" class="moz-quote-pre">Date: Sun, 05 Oct 2025 09:43:53 +0200
From: Remco Viëtor <a class="moz-txt-link-rfc2396E"
href="mailto:remco.vietor@wanadoo.fr"><remco.vietor@wanadoo.fr></a>
To: <a class="moz-txt-link-abbreviated moz-txt-link-freetext"
href="mailto:digikam-users@kde.org">digikam-users@kde.org</a>
Subject: Re: Changing resolution / DPI in BQM
Message-ID: <31192391.1r3eYUQgxm@manticore>
Content-Type: text/plain; charset="utf-8"
On dimanche 5 octobre 2025 09:19:39 heure d’été d’Europe centrale Laurent
Espitallier wrote:
</pre>
<blockquote type="cite">
<pre wrap="" class="moz-quote-pre">Hi everyone!
I don't think I've seen a way to change the DPI of an image in the batch
queue manager, nor in the G'MIC filters. Have I missed something? If
not, do you think it would be easy to implement?
Changing the DPI is possible in the image editor.
Laurent
</pre>
</blockquote>
<pre wrap="" class="moz-quote-pre">"DPI" just doesn't make sense for an image file, as it doesn't have a physical
dimension. Strictly speaking, you can't even define a "DPI" for an image file
(many programs trying to do it anyway doesn't change that).
DPI only makes sense when printing to a physical support, e.g. paper, and then
you are dealing with three directly coupled values:
- size in pixels;
- size in inches/cm:
- DPI, which is (size in pixels)/(size in inch), and can be different for
each direction (hor or vert)...
And even there, DPI is mostly useful to see if you have enough pixels for
decent quality (and the optimal DPI depends on the print size: larger prints
need less DPI).
DPI also makes sense for a printer, as in "I can put so many pixels in an
inch". To complicate the issue even further, printers can also specify how
many dots of ink they can put in an inch. But as they often need to put
several dots per pixel...
TL,DR: DPI is only useful when printing to verify if you reach the required
quality level.
</pre>
</blockquote>
<p>Yet some users find it useful and easier in their workflow to
resize image by changing dpi (in order to display images to
screen, e.g. 300 > 72 dpi) rather than specifying a number of
pixels.</p>
<p>That was implemented in XnView a few years ago <a
class="moz-txt-link-freetext"
href="https://newsgroup.xnview.com/viewtopic.php?t=43382">https://newsgroup.xnview.com/viewtopic.php?t=43382</a></p>
<p>Laurent</p>
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