1

For example, I have a 8819x4961px 300dpi image.

enter image description here

I need to reduce it to 72dpi as required by the company I work for. If I change 300 to 72 in Image Size, it reduces the pixels to 2117x1191px.

enter image description here

But the company is asking for a 3000px width image. So, if I increase the 2117 to 3000 (while in 72dpi mode), will it reduce the quality of the image?

enter image description here

2
  • 3
    Just turn off resampling, then the pixel size won’t change and you can change it to 3000px in width later. Oct 31 '19 at 7:38
  • Stupid question but is this going to be printed?
    – Luciano
    Oct 31 '19 at 15:15
2

If you do that, you will not be increasing the pixels, you will be decreasing the amount of pixels which will remove detail from the image - commonly called "resampling".

Resampling always degrades images to some degree, because it reinterpolates the pixels. However, this has nothing to do with the image quality per-se. An image that is resized can still look good if viewed at 100% (1:1) zoom. If you still want to do it, just make sure you don't overwrite your original image file, since it can't be undone later.

In Photoshop it can be done with a few simple steps, in one go. There's no need to change the PPI and pixel dimensions separately.

  1. Select the Crop tool

  2. In the tool options along the top, set the width to 3000px, and set the PPI to 72.

enter image description here

  1. Hit the Commit button (the tick icon at the right hand side).

  2. Save the image with a new file name so that you don't overwrite your original image file.

1

Just my two cents.

There are two petitions here.

  1. Resampling the image to 3000 px width, which, of course, will... resample the image from 8819px

Use a bicubic sharper. Wich will give you a nice result.

Quality is not a word to use here. Quality is a process on how you work with your files, yes, the image will be smaller in size, but you want to deliver a good quality image but smaller in size.

And that is it...


Oh, yea... the 72PPI.

My analogy of setting an image to 72PPI is like buying a new car, tires, checked, engine, checked, paint, checked. All good...

And for the 72PPI? Just take a post-it and write the number on it and paste it on a window.

It seems the company guy wants it for a website... and a website takes that post it and throws it away.

1

DPI is not a quality measurement, its just a measure of how the image is transfered to physical medium. Strictly speaking defining what a images quality is is questionable in the first place. If you do not account for physical reproduction then only pixels count, if the image is already made then there is not much you can do about those anyway, so only pixels count.

Basically if you change the number of pixels of an existing image then you have a potential problem. If no pixel count changes happen then nothing happens to the image thus no quality loss can happen since nothing changed. However, a viewer may still be too close but that is already in the image limitations to begin with.

Whether this does anything for quality depends on how your image is used after the fact. But if I were your client then i wouldn't be too happy if you interpolated my image and I can spot it...

3
  • I appreciate the explanation. I learned things I didn't know. But as the other user said, I believe I can just turn off resampling while lowering the dpi and changing the width after.
    – Desi
    Oct 31 '19 at 7:56
  • @Desi thats fine but you are still resampling it to number of pixels. Just smarter. But it may still affect your quality... Usually going down in pixels size is problem free. It may even make the image better
    – joojaa
    Oct 31 '19 at 14:31
  • 1
    @Desi also btw. 72 DPI usually does not mean what people think it means. It is the closest thing to saying that DPI value is not set that adobe software have (so if you open a image that has no DPI setting then adobes software will report it being 72). Explicitly setting resolution to 72 DPI is usually meaningless since its usually for screen use purposes and browsers and digital tools readily ignore the DPI setting anyway.
    – joojaa
    Oct 31 '19 at 14:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.