Downsizing an image

[Juliette5EE9]

Hi there. I'd really appreciate some help!

From reading some of the other threads about downsizing images, I understand that you can expect to lose quality when reducing the image size quite drastically. I'm going down to 7% of the original size. The result is very pixelated.

However, where I'm very confused is that I've done this before without any difficulty.  I've previously used the exact same photo format from the same camera, reduced to the same sizes in photoshop, with no pixelation. The only thing that I can think of that has changed in the meantime is that I had to upgrade my photoshop from a very old version.

I've tried resizing them as JPEGs before importing, ticking and unticking the 'resampling' button when resizing, importing them directly from the phone that took the photos to photoshop, experimented with 'bicubic' and 'bicubic sharp' when transforming.... I'm afraid this is as far as my (rather limited) photoshop ability and knowledge goes.

Any ideas for what I can try?!

[c.pfaffenbichler]

Please post example images and the downsampling results for both your current and previous setup. 

If you change the Image Size with »Resample« unchecked there obviouly is no resampling and it is just the resolution that gets changed. 

[Juliette5EE9]

If you don't mind would you explain to me what resampling actually means? It's not obvious to me at all. I just read somewhere that if you were downsizing to print and you don't mind changing the resolution, sometimes the results were better if 'resample' was unchecked.

[Bojan Živković]

First thing to try is Ctrl + 1 after downsizing because you must see image at 100% to judge quality and whether resulting image is degraded or pixelated.

[Juliette5EE9]

Thankyou. Viewing it at 100% makes the canvas appear very small on my screen, although the canvas size is A4 - so not possible to see if pixelated. But when I print, at 100%, the outcome is pixelated?

[Bojan Živković]

What are dimensions in pixels? It may be A4 which is more physical dimension but if that number in cm or in is multiplayed by 72 ppi for example it is not enough for printing so effectivelly you must enlarge image x4 to print A4 at 300ppi.

[Juliette5EE9]

Thankyou! I think this might be it. When I was doing file > new to create a new document the resolution was automatically set to 72ppi. I wasn't changing this because I didn't understand it/had never had problems before.

When I changed it to 300ppi, import and downsize the images and then print I'm not having the pixelated problem.

[c.pfaffenbichler]

»Viewing it at 100% makes the canvas appear very small on my screen, although the canvas size is A4 - so not possible to see if pixelated.«

You seem to misunderstand the issue. 

Please post meaningful images and screenshots to illustrate what you are actually doing to the images. 

And why are you downsampling them to begin with? 

[Juliette5EE9]

I'm certain I don't understand it at all! But I think Bojan Zivkovic was right and it's an issue to do with my ppi settings. Hopefully it is solved now.

If not I will try to post clear images of the problem (and any future problems which I hopefully won't have). Thanks!

[D Fosse]

This isn't as complicated as you think. It all boils down to how many pixels. That's all that matters - all the rest is just derived from that. How many pixels is "enough", depends entirely on the purpose.

100%  view in Photoshop has nothing to do with size. It means that one image pixel is represented by exactly one screen pixel. This is the most accurate way to view the file: you see the pixels directly on screen, no scaling.

Ppi is strictly a print parameter, and it is not a property of the file. It means "pixels per inch", and you should read that absolutely literally. It means exactly what it says, nothing more, nothing less, no hidden meaning. It's a measure of pixel density on paper. This many pixels spread over that many inches of paper.

It does not apply on screen because on screen, there already is a native screen pixel grid. The file just aligns to that. But there is no native pixel grid on a piece of paper, so one has to be defined. That's ppi.