I am attempting to print an image using darktable. On the image information tabl, it is reporting:
However, when I attempt to print to A3, I get:
Why is it printing at such a low DPI?
I am attempting to print an image using darktable. On the image information tabl, it is reporting:
However, when I attempt to print to A3, I get:
Why is it printing at such a low DPI?
A3 is a fairly large print of 297 x 420 mm or 11.7 x 16.5 inches.
Your image has 2770 x 3918 pixels.
Therefore, you have 2770/11.7 (or 3918/16.5) which is approx. 237 DPI.
That implies your image has perhaps a low-ish resolution for a print of such a large physical size.
And dt does not print “at XYZ DPI”. It merely sends an image of HxW pixels to a printer while requesting a physical paper size. The rest is up to you (and the printer driver/firmware).
Please search the forum. DPI is just metadata. 300 DPI is enough for reading distance; an A3 print you’ll probably be observing from further away. After all, 4K (3840 x 2160, so about 8 MPx) is enough for a 45" TV. It all depends on the viewing distance.
You could upscale the image by 10%, but you would not actually add data, just interpolate (spread the existing pixels to cover a larger area).
My local professional print shop provides this advice to his customers and it might be helpful information for many of us here on the forum.
It is possible to up scale digital camera files by as much
as 200% because of the smoothness of the pixel captures,
however scans from film do not tend to respond as well
to increases in size due to the random structure of film
grain.
Common Resolutions
The most common resolution standards you will en-
counter are likely to be:
Web images 72/96ppi
Newspaper 150ppi
Photographic printers 250 or 300 ppi
Offset printing 300ppi
Inkjet printing 360ppi
Which is nonsense, and does not mean anything, of course. The DPI value depends on screen dimensions, even if the screen resolution (e.g. full HD, 4K etc) is fixed. I can display the same photo on my phone, my 14" laptop, my 27" desktop monitor, or my 50" TV. All will have different DPI values, but the size in pixels, the amount of data, will be the same.
A printer has a set physical resolution, determined by its hardware. Let the printing company and the printer driver take care of scaling.
If you don’t have enough pixels, print at a smaller size or view the print from a higher distance. Upscaling does not add information. “AI” upscaling guesses details, and may or may not work well. The only low-res image (640x480, or maybe 800x600) that I upscaled for printing (to roughly 2 or 3 times the size) required upscaling using 3 or 4 models, and then the use of layers and masks in Gimp to assemble the final image from the artefact-free parts of the different versions.
Speaking personally, I have never upscaled an image. If I want more pixels than the camera can give I am known to do panorama stitching, but then the truth is I can’t afford the cost to print my panoramas to their full potential anyway.