Changing resolution / DPI in BQM

[Remco Viëtor]

On dimanche 5 octobre 2025 09:19:39 heure d’été d’Europe centrale Laurent 
Espitallier wrote:
> 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

"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.