Hi,

might be a bug in the JPEG load plug-in or a bug in libjpeg. identify from ImageMagick does indeed show a different resolution. Somewill should have a look at the code and check what identify does differently.

Sven

Bob Meetin schreef:

See example images at www.dottedi.biz/codesamples/broken

The image (vanilla) was taken with an ordinary digital slr. I know it is large - if you check the other image, same problem. It is 300dpi. You can see this if checking with windows image properties or with photoshop. However, when I check in Gimp (2.2) using

Image --> Scale Image

both horizontal and vertical display as 72.

When I load some stock images into Gimp they are correctly display the resolution, be it 150, 300, whatever. So the question, "What is it about this image that is fooling gimp?" Is it a setting in Gimp that I might have innocently messed up or other?

Not only Gimp is confused. I've tried the images in IrfanView and XnView. There is a difference between the two images: - img1_resized.jpg: both XnView and IrfanView think it's 72x72. PIL, the Python Imaging Library, thinks it's 72x72 too. - img1_vanilla.jpg: XnView says ??? x ???, IrfanView leaves the boxes empty, PIL has no DPI information.

That's without looking into the EXIF-data. When I look there, both XnView and IrfanView have XResolution = 300 and YResolution = 300 in both images.

So the difference between Gimp on one hand and Windows image properties and PhotoShop on the other hand seems to be that the others extract the resolution-information from the EXIF-data while the Gimp doesn't.

Hi,

On Sun, 2007-05-20 at 22:40 -0600, Bob Meetin wrote:

But on the pictures from my cameras (I just ran another test with a different camera) Gimp is bound and determined that the resolution is 72.

Well, for pictures from a digital camera the resolution information is meaningless anyway. So why do you care?

Sven

On Sun, 20 May 2007 11:46:07 -0600 Bob Meetin wrote:

See example images at www.dottedi.biz/codesamples/broken

The image (vanilla) was taken with an ordinary digital slr. I know it is large - if you check the other image, same problem. It is 300dpi. You can see this if checking with windows image properties or with photoshop. However, when I check in Gimp (2.2) using

Image --> Scale Image

both horizontal and vertical display as 72.

When I load some stock images into Gimp they are correctly display the resolution, be it 150, 300, whatever. So the question, "What is it about this image that is fooling gimp?" Is it a setting in Gimp that I might have innocently messed up or other?

You need to look at this dpi thing a bit closer

2048 x 1536 pixels at 72 dpi means an image 24.444 x 21.333 inches.

The same information may be presented as

2048 x 1536 pixels at 300 dpi is an image 6.827 x 5.120 inches

If you look at your Gimp preferences you will see that the default resolution for presentation is 72 dpi. Change that to 300 dpi and reopen the image information window. you will see the size of the picture as above.

As you can see, dpi is fairly meaningless. It is what you want it to be.

What is important is the total information in the image.

Owen

Bob Meetin (ontheroad@frii.com) wrote:

And the really befuddling baffling part is that with some of the stock images I looked at Gimp seems to read their resolution fine. So I am guessing that with these stock images there is some image manipulation going on, then gimp is correctly reading for them?

I suspect that the resolution is stored in two places: The Jpeg header and the exif information. My gut feeling tells me, that gimp relies on the information in the jpeg header and other tools look at the exif information.

If these two places contain different information, this might explain your observation.

Bye,
Simon