JS CS2/3, Win XP - Image Size

[Guest]

Is it possible via a script to identify if the image resolution of files in a folder have been changed from 72 pixels/inch to 300 pixels/inch?

Any help would be much appreciated.

Regards
Norbert

[Guest]

Actually I might want to rephrase my earlier post.....

I have a huge number of image files and some of them I think while they are originally 72 pixel/inch, they've been modified to 300 pixels/inch.

Is there a way a script to look for these files as against actual 300 pixel/inch files?

Regards
Norbert

[MarkWalsh]

Do you mean that you want to determine if a file that was originally 72 dpi was resampled up to 300 dpi? If so, then I can't imagine any way that you could determine that, unless you have original documents to compare the modified docs to.

If not, please elaborate more.

[_xbytor_]

Mark_Walsh@adobeforums.com wrote:
> Do you mean that you want to determine if a file that was originally 72 dpi was resampled up to 300 dpi?

Changing the rez doesn't necessarily require a resample.

Regardless, the only way you could tell is if you had photoshop keeping an edit
history for the doc and most people don't have that enabled.

-X

[MarkWalsh]

>Changing the rez doesn't necessarily require a resample.

I wasn't implying that it did, I figured that was the likely scenario that the OP was asking about (I've run into more than my share of people who have resampled low res files and claimed 'Now they're high res!')

[Guest]

Hi Mark and X,

The files are supplied by clients and while they are originally 72 pixels/inch, the resolution has been changed to 300 pixels/inch. While most often if the pics are going to be used large enough in Indesign, the forced resolution change is pretty obvious because of the visual pixelation but sometimes, if used tiny, they are not very obvious unless scrutinised very closely.

Is there any math identifier whatsoever to identify either this sort of pixelation or any histogram unique identifier (I'm just clutching on strings here).

Any help... Most welcome....

Regards
Norbert

[MarkWalsh]

Again, my question is are you asking if there is a way to find out if the files have been resampled (as opposed to resized without resampling)?

If the answer is yes, then aside from any saved history as mentioned by xbytor, the only way I could imagine is that if you have the original file (72 dpi) before the resolution was changed to 300 dpi so you can compare the dimensions of file a to file b.

If the client is sending you files at 300 dpi, and you are trying to determine if they resampled low-res 72 dpi files to 'create' those 300 dpi high-res files, then you are pretty much out of luck.

There is no way to determine arbitrarily if pixels have been resampled.

[Guest]

Hi Mark,

I don't exactly know what my client is doing but I know that the pixels/inch is showing 300 pixels/inch but visually the image looks pixelated so I am presuming that what the client is doing is simply changing the value in the pixels/inch field to 300 from a low-rez file when we ask to be sent hi-rez images.

Thanks for your time......

Sincerely
Norbert

[MarkWalsh]

Yes, I have seen this quite often. I'm still amazed how many people will, when asked for a copy of their company/product logo for print production (preferrably vector), I'll receive a crappy Jpeg from their website.

Unless you have a 72 dpi file and a 300 dpi file of the same image to compare, there's really no way to tell if the image has been resampled. And even if you do have 2 files to compare, there's no way of telling if the 300 dpi file was resampled up from the 72 dpi file or the 72 dpi file was resampled down from the 300 dpi file. The best you could do would be to compare the pixel dimensions (if they are the same, then the files weren't resampled)

[_xbytor_]

> The best you could do would be to compare the pixel dimensions

Good point. The pixel dimensions are the only thing that matter. DPI and PPI are
useless unless you're exporting for print or the the web.

The pixels dimensions tell you how much information is in the image. That (and
bit depth) are the only numbers that matter.

-Z

[_xbytor_]

> The best you could do would be to compare the pixel dimensions

Good point. The pixel dimensions are the only thing that matter. DPI and PPI are
useless unless you're exporting for print or the the web.

The pixels dimensions tell you how much information is in the image. That (and
bit depth) are the only numbers that matter.

-Z

[Guest]

Good point about comparing pixel dimensions but how often does a client send both a 72 DPI file as well as a 300 DPI (resampled/resized) file?

Norbert

[Michael_L_Hale]

I think the bottom line is the image's quality and that is subjective. Even if the image has not been resampled it still may look bad if they sent you a jpeg with high compression.

Some things can't be scripted.