Blender DPI settings (Pixel size calculator)

Hi guys, this is a proposal i submitted to the bledner devs, the idea was created by me (and intrr) as we found we were often rendering images for print (i.e. busines cards, CD covers, graphics on a page layout) this feature would allow you to specify the real dimensions of a render in Inch’s or Metric, and then Blender would be able to render it to the correct pixel size.

it was rejected by a single person for the following reason…

“It will create bug reports” (in relation to formats that eitehr don’t support DPI information, or new formats that DPI info writing was never coded for)…

i am wanting to know how much of the community would like a feature like this. i have had an extremely large amount of support from people so-far to keep pushing this idea. but have been rejected a number of times by this person.

All i want is for this feature to get in. untill there are enough people supporting the feature i doubt it has a hope in hell of getting in.


I spend all my days at work preparing media for print and have a background in graphic design. I would use this feature and dont see any reason to not include it.

If its ‘only’ a calcultor that dosnt write DPI info to the saved render then I dont see the objection regarding bug reports holding any weight.


I’d definitely use that, great idea!


Gee, I wonder who ‘this person’ could possibly be :slight_smile:

I agree that the feature seems like it would be of great use for print work. A possible solution is that those features are only shown for formats that support them perhaps. Also I think he didn’t care for the method the interface had been done (as I recall from emails on bf-committers…)

Matt Ebb (broken) might be a person to talk about regarding interface suggestions.

Another way of improving the chances of the idea being accepted is for a patch to exist in the patch tracker.


well as a render size calculator it is still very valuable, so it should always IMO be enabled. saving to formats without DPI fields IMO is not really an issue.

the blank space on the panel could easily have a list of the formats DPI is supported on.

the form it was in was not an issue AFAIK, the original dislike of the interfacing with the panesl was because the DPI settings had been put along-side the render settings. rather than a context sensitive tab like this concept (somewhat like the yafray extra tabs)

Another way of improving the chances of the idea being accepted is for a patch to exist in the patch tracker.

good idea. now all i need is for someone to get the code up to scratch (intrr i would hope still has the original code from the first implimentation)


I dont know anything about programming, but this doesent sound too complex to do?

Very nice idea! Now i just a throw a guess about the size cause i dont always want to check the correct size from pshotoshop or calculate it somewhere.

I’ve been using “Art Director’s Toolkit” when I’m too lazy to reach for my vintage 1979 HP32E calculator (with red LEDs) for calculating image sizes. If that feature was included in Blender I would use it constantly.

If the image format does not support DPI info it should be just ignored at saving. We have to bring the renders in Photoshop for (at least) colour correction/separation anyway…

what if app could render ‘anim’ to multipage tiff - ?

Well well… that bug thing just annoys me… here’s an example of how I think this little calculator should work… (bug-free)

You put your desired size in the unit you want and set the DPI… and blender automatically sets the according pixel size… pretty clear (and useful)

Now, when you press Render (actually, when you press F3 to save the image) blender checks the file format you want to save in, and in case that DPI stuff is not supported in that format a little dialog will appear telling you “this file format doesn’t support DPI information, no DPI information will be saved” but the image will still have the right pixel size…

As simple as that!
I don’t see any buggy troubles with this feature… %|

I think it is a pretty cool idea! :smiley:

well that dpi thing is pretty handy. sofar i always need to render everything in a bigger size and than transform dimensions in photoshop, with a build in dpi setting blender will do the work for you. i think dpi and in/cm dimensions instead of pure pixels would be great.

hmm “instead” ??

I 100% agree with the idea of having a DPI setting in blender. But for sure, this one need to be included as an “option” that is not set on default. Once it get activated, the new buttons appear for us to put the values in. But yea, that would be VERY handy sometimes!

I’d like a “real world” size calculator in Blender. Then again, I’d also like a definitive way to measure stuff in blender. To keep my sizes straight.
So that when in the future, I make a person in 1 file. Then in another file I make a “house”. The person isn’t a 10 foot tall giant in comparison to the “house”.

This is a great idea. I hate having to open up a calculator program just to determine the pixel dimensions. Since we’re talking about print, how about CMYK support (I can hear the programmers cringing).

I’m a print designer by trade and would LOVE this feature to be added, would make life so much more easy!! Please please add this!!

That sure is a useful feature. I have nothing against it being put in the render buttons, although i think it should be made obvious that it is only a calculator.
EDIT: Duh… didn’t look at the pic properly… %|

I would also like to point out, that it could also be done as a python script, without losing functionality.

Basse kindly created this DPI calculator in python.

just save the following text as a .py file and put it into blenders script path.

thanks basse, sorry for the delay in posting it, its been on ym Todo list for ages.


Name: 'DPI calculator'
Blender: 239
Group: 'Help'
Tooltip: 'calculate dpi thingys'

import Blender
from Blender import *
from Blender.Scene import Render

units = ['cm', 'mm', 'inches']
factors = [2.54, 25.4, 1]

scn = Scene.GetCurrent()
rdr = scn.getRenderingContext()

#factors = {'cm': 2.54, 'mm': 25.4, 'inches': 1}

def main():
	unit = Draw.PupMenu('unit %t|cm|mm|inch')
	if unit == -1: return
	dpi = Draw.PupIntInput('dpi: ', 300, 72, 600)
	if dpi == None: return

	sizeX = Draw.PupIntInput('sizeX (in '+units[unit-1]+'): ', 10, 0, 10000)
	if sizeX == None: return
	sizeY = Draw.PupIntInput('sizeY (in '+units[unit-1]+'): ', 10, 0, 10000)
	if sizeY == None: return
	confirm = Draw.PupMenu('ok? %t|unit: '+units[unit-1]+'|'+str(dpi)+' dpi|x: '+str(sizeX)+'|y: '+str(sizeY)+'|------|convert!')
	if confirm != -1:
		rdr.imageSizeX(int((sizeX /  factors[unit-1] ) * dpi))
		rdr.imageSizeY(int((sizeY /  factors[unit-1] ) * dpi))



Sounds like a good idea to me.

The Print Calc tab could also be used to enter the dimensions of a piece of paper and then have an additional button which sets blender’s render size (x & y) for that print size at the required DPI.

Most useful.

Can’t imagine why a developer would object to something which is evidently quite a useful feature %|

So, let me get this straight, this will create the distance as if it’s in the real world, so that if it’s a inch in blender it will render a inch on the screen ? Or is this more of a cad feature in Blender ?


this is for doing print work - an image needs to have a certain resolution at a particular size - ie 900 dots per inch for a 1 inch by 1 inch image - which would come to a particular pixel width and height. Thus this would give automagically the correct pixel height and width for the specificed width and height and DPI. Has nothing to do with CAD features.


So it has to do with size on paper or is this just choosing the resolution ?