How to change a photo's DPI?

[Colin Southern]

Yes. But Sylvia said her current files was 480 ppi, and I guessed, possibly foolishly, that they want the same sized image.
What could be more of a concern is that no colour space is mentioned. If the 'administrators' aren't capable of downsampling it's entirely possible equipment either isn't properly colour managed. Let's hope the image is a black and white!

Tim

Hi Tim,

What they're asking is impossible without more info ... unless I'm missing something, "the same sized image" is probably also an unknown with the image probably hasn't ever been printed; and if it had (or the "dimensions" had been noted on some program) then why would 480 PPI be a problem, as it exceeds the 300 PPI requirement. Just doesn't make any sense.

About the only time any of this would make any sense would be if they said they wanted to print a 12 x 8" image at 300 PPI (thus 3600 x 2400 pixels required), and the version the OP had supplied electronically was something considerable less than 3600 x 2400.

[Noice]

assuming its being printed, its safe to say she should have it in AdobeRGB color space.

as for the sizing, i would keep it on the larger end because it is always better to shrink a large image to a smaller print than to enlarge a small file.

the only problem i see with having a high PPI is that the file size becomes considerably larger

[Macmahon]

Hi Tim,

...

About the only time any of this would make any sense would be if they said they wanted to print a 12 x 8" image at 300 PPI (thus 3600 x 2400 pixels required), and the version the OP had supplied electronically was something considerable less than 3600 x 2400.

Agree entirely.

[Black Pearl]

I feel this has become a little over complicated.
The simplest thing for the OP to do is just change the dpi/ppi in Photoshop (or similar) without resizing the image?

That way the company involved get the file at the required 300ppi - there are no extra or less pixels - the actual file will be the same - the software involved in changing the parameters won't have an impact on the quality - yes it will now show to print smaller but the printers involved can then alter the file (if required) using their equipment which will likely be better set up than an individuals for their specific machine.

eg.

Using Photoshop: un-tick the Resample Image box and change the Pixels/Inch figure to 300.



I understand what everyone is saying about dpi and ppi and what size picture is going to be printed but this is the simplest and safest way to keep the original picture quality.

[Colin Southern]

I feel this has become a little over complicated.

It wouldn't be if someone would just tell us the size it needs to be printed

That way the company involved get the file at the required 300ppi

Yeah - but it's just smaoke and mirrors - isn't changing anything.

yes it will now show to print smaller

No - bigger. It's 480 PPI Now.

but the printers involved can then alter the file (if required) using their equipment which will likely be better set up than an individuals for their specific machine.

One would have thought so, but if that's the case, why is the OP being asked to do something that the printers should be able to do in 3 seconds flat?

[Black Pearl]

Smaller...bigger...DOH!

At a guess the emails will be going between the OP and a secretary who has been told to get a 300dpi image but doesn't have the first clue what that is or why dpi and ppi are different. Nothing against them its just a typical business structure where "the proverbial" always runs down hill.

Give them a 300ppi file without any resizing and leave them to it - simples