Resolution Question

[Jarviz]

I've recently noticed that when I save a photo that I've been adjusting in Photoshop, it saves it at a resolution of 72, with a height of 29.16 X 20.83 inch.
When I send this out to the Photo Developer, should I be adjusting the resolution to around 300 or do they automatically increase the resolution to reduce the photo size, in this case to
5 X7 inch

[Stephen M]

Photoshop should honour the original resolution in the file that it opens, and it should resave with the same resolution.

We are not talking of total pixel count, which is not changing - just the apparent resolution which thus affects the canvas print size.

Keep in mind that some file formats do not contain the header info describing resolution, so everything is considered 72 ppi in that format, I think JPEG is an example of this.

If you print a JPEG from a 'dumb' bit of software like a web browser, it does not understand resolution/canvas size - so it treats it as 72 ppi and thus you get a huge canvas size print! I think Photoshop can understand the resolution comment in a JPEG file, but perhaps not all other software.

So, what is the original res when you open?

What is the res when you edit and save but not close?

What is the res when you save/close/reopen?

What file format are you saving into for output?

Do the output people understand that you want a 5x7? I guess so as they are not charging you for a 29x21 print!!! <g>

On the resizing issue, the image/image size command in Photoshop would be used with resample image _unchecked_ or disabled, so that no pixels are added or removed - just the apparent resolution/canvas size would be changed (total pixel count and file size stay the same).

I seem to have introduced more unanswered questions here than answers...

Stephen Marsh.