Hi. All of my renderings have been exclusively just digital pieces, but I have to resize my renders to 24cm x 30cm size with 300dpi for an upcoming project, and I have difficulty with converting as I don’t really know.
I am also including the blender file as well.
I had originally rendered this is blender 2.8, Cycles engine, at 1000 samples with denoising at (Resolution X) 1920px by (Resolution Y) x 1640px with 110% resolution.
I will be now rendering this in blender 2.81a, still using cycles.
I appreciate you bringing this article to my attention Kolloom. I was able to understand a little bit of the information that had do to with pixel sizing, but I’m still not grasping the overall picture. I also do not have photoshop so I will have to use another photo editor.
So then there wouldn’t be a need for me to use a photo editing application? I mean, I could if I wanted to do some post processing revisions, but I wouldn’t have to do the conversion of pixels to cm in blender itself, is what i’m understanding by your reply John.
You just have to convert centimeters to inches and multiply by the desired DPI figure. That will give you exactly the resolution for print without having to scale anything up or down in post. You might still benefit from making sure the final document is set to 300 DPI to make it easier for print software to import it.
That same resolution (2835 x 3543) could be 24cm x 30cm at 300 DPI or 48cm x 60cm at 150 DPI or even 12cm x 15cm at 600 DPI. You’ll have the correct resolution for any of those.
You could just click in the Resolution X text field in Blender and type in 24/2.54*300 to have Blender work everything out for you. Replacing 24 in the example with whatever cm size is desired. Let Blender do the work
I know you said you didn’t have access to Photoshop, but I’ll post this here anyway. You might be able to find a comparable feature in whichever photo-editing software you use. In Photoshop you would bring in an image and crop it without any values in X and Y and with the desired px/in (which for all intents and purposes is dots per inch in print terms) and “crop” it. All this would do is kinda label the image as being that resolution. That means that when it is brought into Indesign or similar, the software knows it’s meant to be 24cm across at 300 dpi and not 100cm across at 72 dpi or whatever.
It’s just the number you have to use to get inches from centimeters. It would be 25.4 if you were working in millimeters.
You got it
I worked in print for 21 years and still not really sure why we stick with dots per inch even when everything else is metric over here. All though come to think of it we used all sorts of weird mixed units and systems in newspaper production. Width in columns, picas and points, depth in centimeters, type size in points.
You can do this kind of conversion in GIMP (which is free) and probably Krita as well, also free.
You’ll have to read the instructions and there are some settings that are optimal for not losing too much detail if you are upscaling an image. However, I think re-rendering to the desired size is probably the best approach to keep image sharpness to a maximum.
Hey John, I took the information you provided me, and made a revision to one of my renders. Would you be able to take a look at it and confirm if I did it correctly?
This was the file when I rerendered it:
And this was the file once I took it into medibang and changed the dpi and switched to cm
That works correctly. It shows in Photoshop as being the right dimensions at 300DPI (it shows as 118 px/cm which is the same thing.). I’d stick with pixels per inch/dots per inch when designing for print. It’s what everyone tends to expect.