Post Reply 

DPI of PNG after Export is always 72

Sep 7, 2013, 05:04
Post: #1
DPI of PNG after Export is always 72
I have an .xcf file that contains my image. It is set to print at 5"x3" at 300 DPI. So my image is 2500 x 1500 pixels. When I export to a PNG my pixel resolution stays constant at 2500x1500, but my DPI drops to 72. This causes InDesign to pick up the image and think its 34.72" wide!

Did I do something wrong? Why is my image always exporting to 72 DPI regardless of my settings on both the Print Size and Image Size windows?

Source image:
http://i.imgur.com/xcQ9oHN.jpg

Image properties according to Adobe Bridge:
http://i.imgur.com/CYs6oWR.png

Print attributes from GIMP:
http://i.imgur.com/MTHgxRZ.png

Image Scale attributes from GIMP:
http://i.imgur.com/aiGvsj1.png
Find all posts by this user
Quote this message in a reply
Sep 7, 2013, 06:36
Post: #2
RE: DPI of PNG after Export is always 72
Hmm...So I searched for a measurement converter. Something with your sizes are off, this online free calculator should help you troubleshoot it better. It converts from pixel to inches, inches to pixels. (plus dpi depending on your monitor size/setting)

http://auctionrepair.com/pixels.html

Generally, if your displaying it on the web, you don't need to worry about the dpi

*You mentioned your original xcf was 3x5 " thats 1500 x 900 px. So there is inconsistancies of when you save the file & import it into indesign.

After changing the size, leave gimp open & see if you can import by copying from gimp & pasting into indesign.
Visit this user's website Find all posts by this user
Quote this message in a reply
Sep 7, 2013, 08:13 (This post was last modified: Sep 7, 2013 08:33 by rich2005.)
Post: #3
RE: DPI of PNG after Export is always 72
Well it is working here.
I hope you do not need to resort to a calculator for 2500 x 1500 pix divided by 500 dpi equals 5" x 3". Wink

My guess is that you did not set the print resolution immediately before you exported from xcf to png.
[Image: ayp2cQi.jpg]

Image menu -> Print Size
If you did that and it failed then what OS and version of Gimp are you using?

One thing you can use in Gimp to demonstrate print size.
In the View menu untick dot-for-dot for each image.
These two. Bottom is your image from imgur. Top is that image which has been resaved & reopened with print size set to 500dpi as above.
Both still 2500x1500 but now you can see the relative print size.

screenshot: http://i.imgur.com/6ATWw3a.jpg

Just to prove it carries over, this is the exported image opened up in PS7
No problem there, document size is 5"x3"

screenshot: http://i.imgur.com/MjDqolj.jpg

** https://www.gimp-forum.net/ now answering questions**
Find all posts by this user
Quote this message in a reply
Sep 7, 2013, 09:18
Post: #4
RE: DPI of PNG after Export is always 72
If all else fails Wink Had to check the syntax

You could convert the dpi using ImageMagick and command line

Code:
convert input72dpi.xcf -density 500 -units PixelsPerInch output500dpi.png

The latest version of IM is quite good with the .xcf format these days but you could use any input format, say another png, that IM supports.

** https://www.gimp-forum.net/ now answering questions**
Find all posts by this user
Quote this message in a reply
Sep 9, 2013, 19:48
Post: #5
RE: DPI of PNG after Export is always 72
Quote:Asking the obvious: the "Save resolution" is check in the PNG save options? 72DPI is the default resolution in most image software for historical reasons so when you see "72DPI" you can think "missing".

Winner winner, chicken dinner. A key component I forgot to mention (and a good example of "don't work after 3am") is that I'm scripting this. I misread the script documentation and had to puzzle out which parameter of "file-png-save2" is the "save resolution" parameter (tip: 4th to last).

Setting that to TRUE saved my resolution (of course it did).
Find all posts by this user
Quote this message in a reply
Post Reply 


Possibly Related Threads...
Thread: Author Replies: Views: Last Post
  PNG HELP ajbuccieri 1 180 Nov 8, 2018 09:03
Last Post: paynekj
  Transparent Layer Changing To Black instead of White after Export JustAmanda123 2 3,524 Jul 28, 2018 17:06
Last Post: abajan
  DPI problem Wasew 1 260 May 23, 2018 06:15
Last Post: paynekj
  PDF export problem Buntu Bunny 5 9,033 May 18, 2018 20:56
Last Post: paynekj
  GIMP 2.8.18 on MacOS Sierra freezes on export yroeht 2 290 May 17, 2018 20:24
Last Post: paynekj

Forum Jump:


GIMP ForumPortalArchiveContactTermsRSS