Opening at a different resolution to what they were scanned at

[sarahc51668357]

Hey all

So I've scanned 26 slides all at 1200 PPI (I checked to make sure) 

15 of them have opened in Photoshop at that resolution and 11 are opening at 300 PPI.

I've checked the original files to make sure they were scanned at 1200 and they absolutely were. I've also tried opening them via bridge and also straight from the file and the same thing happens. I'm at a complete loss.

Can anyone help?

[D Fosse]

The question is, how many pixels wide x high? A digital image file doesn't have a size - it only has pixels.

Pixels per inch (ppi) is just a way to translate pixels into a physical size or vice versa.

Once you have the pixels in the file, you can assign any ppi number you want, and this defines a physical size.

Pixels per inch.

[sarahc51668357]

Fair point

One of the ones that's that is opening at 300 ppi is 1577x1066 And one of the ones opening at 1200 is 1580x1077

[pixxxelschubser]

OK. It's almost the same size (in pixels).

So everything is fine. If you now need 1200 ppi, then open the image size dialogue and set the resolution to 1200 ppi (important: without recalculation!!!).

This will not change the number of pixels and you can now save the file again.

[davescm]

Check your scanning software settings. Scanning software usually allows you to separately set two ppi numbers.

The first is the resolution of the scan, which decides how many pixels will be used to capture each inch of the image being scanned.
The second is the ppi value assigned to the captured output image. This merely tells software such as Photoshop how big a print of the scanned image should be on paper. If viewed on screen the ppi value is ignored.

As an example a 36mm x 24mm slide scanned at 1200ppi will have 1700 x 1134 pixels.  If the output file is then assigned 300ppi it will print at 5.67 x 3.78 inches on paper.

Dave