PC jpeg's change size on Mac

[bbmeister]

Would anyone know why when we receive jpeg files from clients saved in Photoshop PC format and we open them on a Mac they change size/res.
To make it more clear, we update in pixs Quark and the sizes are fine, than edit original in Photoshop to color correct them, update in Quark and the jpeg places much smaller.

eg.
original: Dimensions: 45.333" x 34" at 72 dpi
after color correction: Dimensions: 8" x 6" at 160 dpi

If you do the math the proportions are correct, but with the percentage of the jpeg placed in Quark, they update much smaller.
I'm not sure I can place the fault on Quark this time, it appears to be a Photoshop problem.
Thanks
Bobm

Edited by: Bob Meister on Apr 8, 2008 8:57 AM

 

[almaink]

Re: PC jpeg's change size on Mac

When I first saw this I thought it was Photoshop to, but have you tried opening the image in Photoshop before editing from Quark and check the size in Photoshop? When this happened to me for the first time, I found the customer had done a switcharo, that being they had two image files with the same exact name and somehow either Quark collected the wrong one or they did manually.

 

[bbmeister]

Re: PC jpeg's change size on Mac

No, when the graphic is updated and OK in Quark the More Info shows original: Dimensions: 45.333" x 34" at 72 dpi.
As soon as I open in Photoshop, in any way (open, double clck, or from within Photoshop)it changes to 8" x 6" at 160 dpi
Thanks
Bobm

 

[okjohn]

Re: PC jpeg's change size on Mac

Dimensions: 45.333" x 34" at 72 pixels per inch =
Dimensions: 8" x 6" at 160 pixels per *cm*
Are you sure photoshop is reporting measurement in inches or centimeters?
This has happened to me many times from pc to mac.

 

[bluskool]

Re: PC jpeg's change size on Mac

I am pretty terrible at math, but I don't think that works out right. 35.333" x 34" at 72 PPI should equal 20.4" x 15.3" at 160 PPI. If you are getting 8 x 6, then something crazy is going on.

That is interesting, however, because I have noticed that if I download a picture from the internet or receive it via email and open it in Photoshop, Photoshop always reads it as 72 PPI even when I know it was saved at 200 PPI.
I have made it a habit to do a quick option + command + I and if the resolution is not 200 PPI, I uncheck the resample image box and change it to 200 PPI so that I know (in inches) what I'm working with.
I guess Photoshop doesn't know what you want the resolution to be set at so it guesses based on where the image comes from.
Downloaded images will default to web standard 72 PPI and I believe that Quark's default resolution is 160 PPI so that might be why you are getting that number from Photoshop.
I don't think this is a bug so much as just a nuance of digital images. Photoshop is just reading the pixel dimensions and has to guess how you want PPI set if it is not available in the metadata.
Unchecking the resample image box and setting PPI is just part of normalization like assigning sRGB to untagged images and converting to a better editing space.
However it sounds like in your case, something is just screwy. I would have to guess, however, that Quark is the problem. Try opening the pic first in Photoshop before Quark gets it. Whatever pixel dimensions it has are going to be right unless your copy of Photoshop is bad, but if that was the case, you would probably notice it more often than just when you open images from Quark.

Dan R.

 

[okjohn]

Re: PC jpeg's change size on Mac

If you read my reply again you will see my solution was that the resolution might be showing in *PPC* (pixels per centimeter) *not* PPI (pixels per inch) in Photoshop as you suggested. Check that in Photoshop!

 

[bluskool]

Re: PC jpeg's change size on Mac

Well, if you read my reply again you will see that I was responding to OP who said that the proportions were correct. He said the picture, once saved, is coming back into Quark a different size. If Photoshop is just reading centimeters and he doesn't change the size, then the fact that it was in centimeters would not have an effect on the size in Quark. Since it does have an effect on the size in Quark, I would have to guess that the picture is actually a different size, but Quark is not recognizing it properly until OP opens it from Quark, color corrects and updates.
More than likely Almaink was right when he said that the picture is probably not what Quark thinks it is. I have changed a picture from color to gray and Quark still thinks its color and won't let me update.

Whether Photoshop is measuring in centimeters or inches would have absolutely no effect on what the actual pixel size of the picture is at all!

 

[acp]

Re: PC jpeg's change size on Mac

We had this happen to us a while ago and I found this link on Quark's site.
It didn't make sense to me then and still doesn't. Maybe it will to one of you...
http://www.quark.com/service/desktop/support/techinfo/kbase_view.jsp?faq_id=1709

 

[bluskool]

Re: PC jpeg's change size on Mac

It is just saying that the jpeg filter for Quark was not programmed very well and Quark doesn't feel like fixing it. Probably because most people don't import jpegs into Quark. Just use tiff or png.
Jpeg is really only useful for the web, but even then png is better because it's friends with the alpha channel.
You might just need to update Quark.

So, really, this was Bob's original problem. Photoshop was reading the file correct, but Quark resamples it to 72 PPI. It probably didn't happen when his customer imported it because they had the updated jpeg import filter, but when Bob reimports from Photoshop, Quark resamples it.

 

[bbmeister]

Re: PC jpeg's change size on Mac

Thanks bluskool,
I was leaning towards Photoshop being the culprit but your explanation of the Quark support makes sense. It was foolish on my part to not know that *QUARK* was the true culprit.
Thanks again
bobm