Why is Windows image Resolution not always same as Photoshop value for same file.

Report · Nov 08, 2018

If I create an image in PhotoShop Elements setting size and resolution

and save it as a jpg file I can look at the resolution using Windows file details

by selecting to display horizontal resolution. PhotoShop element writes out dpi to the

header of the image file.

If I take an image from say a camera, modify the dpi to match

the coin I have photographed and save the file Photoshop does not

always save the new dpi to header of image file. It writes to some Meta data

since it knows the value when I open the file with photoshop.

How do I get photoshop to update the dpi recorded in header without needing

to create a new blank image with required resolution and copying camera image

to new file.

Thanks for any advice

Report · Nov 08, 2018

Moving to Photoshop Elements

Report · Nov 08, 2018

lakdiva wrote
If I create an image in PhotoShop Elements setting size and resolution
and save it as a jpg file I can look at the resolution using Windows file details
by selecting to display horizontal resolution. PhotoShop element writes out dpi to the
header of the image file.
If I take an image from say a camera, modify the dpi to match
the coin I have photographed and save the file Photoshop does not
always save the new dpi to header of image file. It writes to some Meta data
since it knows the value when I open the file with photoshop.
How do I get photoshop to update the dpi recorded in header without needing
to create a new blank image with required resolution and copying camera image
to new file.
Thanks for any advice

Menu Image >> Image Size

Uncheck resample if you want to keep the original size in pixels (only way not to lose quality)

Enter your new ppi resolution (pixel per inch, not dpi, dot per inch is a property of the printer)

You'll see the new size in inches corresponding to the new resolution.

Save over your original or create a new version (copy).

The only meaningful size of a digital image is in pixels.

The resolution or physical size in inches are up to you to choose. If you keep the pixels size, the resolution will be calculated from the chosen inch size, or the inch size will be calculated from the resolution.

Note that if you save your new resolution image over the original by resampling, you'll lose quality.

If you save over without resampling, you also theroreticall lose quality when saving in jpeg format (lossy compression issue) but that may be negligible.

Report · Nov 08, 2018

I do understand the basics of image transformation which was not my question.

I did find how to update the X and Y resolution using exiftool

https://www.sno.phy.queensu.ca/~phil/exiftool/

The need to update X and Y resolution is that it is visible via the OS and not

just to PhotoShop via Metadata

Not sure why my PhotoShop Elements does not update when I just

change the resolution, It does update if I transform the image

Maybe a bug in my old Version 6 of PhotoShop Elements,

Report · Nov 08, 2018

lakdiva wrote
I do understand the basics of image transformation which was not my question.

I am afraid I don't understand the basics of your question...

The need to update X and Y resolution is that it is visible via the OS and not
just to PhotoShop via Metadata

Yes, it's visible from the OS (I am in Windows). It's also visible to the editor (file >> file info) as well as in the organizer ( Information panel, exif section) . You don't need to use exiftool to see it.

Not sure why my PhotoShop Elements does not update when I just
change the resolution, It does update if I transform the image

From where do you change the resolution? From PSE6, from exiftool, or...

If you save your image after changing its resolution in any Elements version, the resolution is updated in the metadata header as well as in the catalog. If you change the resolution and don't save the file, you have done nothing. Just tested with PSE6.

Report · Nov 09, 2018

What is visible to OS is Exif/X Resolution and Exif/Y Resolution

and it is also visible via PSE6 file info for some file, but I can't edit it with PSE6

When I change Resolution using PSE6 Image > Resize > Image size

with or without any transformation of the image and save the image, it does not

always update Exif/X Resolution and Exif/Y Resolution.

Still not worked out under what conditions it does not.

So in these cases, I now just use Exiftool to update these two parameters.

I use PSE6 on Windows 7, but my website is hosted on a Linux server on

which I want OS to be able to see the Resolution I set.

Thanks for your comments.

Report · Nov 09, 2018

When I change Resolution using PSE6 Image > Resize > Image size
with or without any transformation of the image and save the image, it does not
always update Exif/X Resolution and Exif/Y Resolution.

It always updates for me, in all Elements versions.