Image quality

[irsn]

I've just made a magazine on InDesign being careful to only select high quality images (using the large tool on google search). I also used the "display performance"- "high quality display" in InDesign to ensure the images were high resolution. However, I have gone back to my document and found that apparently all the images are now below 100 pixels per inch (I think they were initially over 200 pixels per inch). When we previewed the document for print all of the images were blurry and highly pixelated. Does anyone know how to fix this so that the images actually appear in high resolution? I think I've tried everything but getting desperate as I need to send it to print asap. Thank you so much

[BobLevine]

Where exactly did you get this images? Did you enlarge them in InDesign?

[irsn]

I got the images off google. Depends on the image but for most of them I actually made them smaller 

[BobLevine]

So, you're just using other people's images without permission?

[irsn]

Yes because it is an internal school magazine for very few people! 

[Marianne-Deiters]

The specification 200 px/inch does not say anything about the quality of the picture. Open the "Links" panel, mark a link and look in the details at the effective resolution.

[Anna Lander · Accepted solution]

"Display performance" controls just the screen view, it does not affect the output image quality.

Check Effective PPI in Links panel like Marianne says. If the original was 200 PPI and you scaled it for 150-200%, the final (Effective) PPI becomes under 100 PPI. Change the size in Photoshop and set the final resolution at least 250 PPI for good printing. Images can become a bit blurry, but at least not pixelated.

[irsn]

Ah thank you I think you're right. I've opened the links panel and it says the effective PPI is under 100 PPI (often around 75). Sorry for all the questions but how do I change the size in Photoshop?

[Marianne-Deiters]

You have to enlarge an image at least four times, that will be a pretty bad quality, since only similar pixels between the existing ones are calculated when interpolating. You will find the Image Size command in the Picture menu

[Test Screen Name]

Web images are NOT a source of print-ready material. Web graphics are absolutely useless for quality printing, and getting big ones won't make much different. To get good quality press images you need to make them (e.g. photograph them) or buy them.  By the way, internal school magazines are NOT outside copyright and what sort of example does it set to use or encourage stolen images?

[Eugene Tyson]

Well, it depends on what size they are effective for printing them. If they are good enough effective resolution then there's no reason not to use them.

[Gusgsm]

Resolution and quality are not the same or, in other words: Quality is not a subset of resolution but the other way round.

If you are grabbing images from Google search (we will go with the "internal magazine for a school" version), size is just one parameter but, as they are "from anywhere" (no irony here), you are not so sure about their quality as if you were buying from an agency or photographer.

That means that, once you have downloaded them in your computer, it would be a very good idea to examine them with Photoshop looking for defects (artifacts). I'd look specially for artifacts caused by excesive compression.

And for some uses and jobs, Internet can be a source of good enough pics but you've got to remember that you get what you pay for. And, legally speaking... well, you know where you stand.

Best regards

[irsn]

Thank you so much that's so useful. I hadn't realised picture quality and resolution were a different thing that makes more sense.