Picture resolution/Photoshop question

Started Apr 28, 2017 | Discussions thread
OP guiri Veteran Member • Posts: 4,237
Re: Ehem, I think I may have screwed up...

You used the term "sample it down", and that necessarily means a reduction in the number of pixels.

If you request a reduction from 300dpi to 72dpi, asking the program to resample:

for each part of a photo which starts 300 pixels wide, you will end up with only 72 pixels to represent that same part of the photo.

So if you take an original photo, then reduce it to 1000 pixels wide, then further resample it using a 300 : 72 ratio, you will produce a final version 240 pixels wide instead of 1000 pixels wide.

If you instead simply "re-label" your 1000 pixel wide version as being a 72dpi image, by un-checking the option to have your picture content physically resampled to fewer pixels while applying that change - then it will remain visually identical on screen. Because it will then retain its 1000 pixels width.

Or... you could simply not bother with this final step since on the web, nobody knows or cares anyway WHAT dpi a given photo version might claim to consist of. It's beside the point. All that matters is: how many pixels big.

It's been so long since I did anything and when I do something like this, I start questioning things, even things that I knew before so I just want to confirm before continuing. For some reason I seem to think I got better results when doing stuff like this years ago. Maybe I'm just not remembering correctly.

Perhaps the best way - meeting both the practical need for a 1000 pixel wide image, and your desire to have this then report as a 72ppi version - would have been to have requested this 72ppi labelling as part of your initial reduction to 1000 pixels wide.

Make your selections in this order, noting what happens to the pixel dimensions as you do so:

regards, RP

I may not be using the correct terms and the only reason I do the 72 dpi resolution is because I learned a long time ago that this is what the web or screen resolution is and also, no sense in uploading a 300 dpi picture because the file size will be bigger but because of the screen resolution, no one will see the difference...?
Anyway, I'm using CS2 so my options are different. I have SCALE STYLES, CONSTRAIN PROPORTIONS (which I check) and RESAMPLE IMAGE which is set to Bicubic.
When I click on Auto, I get another dialog box which asks me how many lines per inch, Draft, Good or Best quality and depending on what I choose, it changes it in the regular window to 144 (best), 108 (good) and I'm assuming 72 for draft.
Also, normally when I resize something, I change the resolution first and then the pixels/size before I hit ok 'cause I know that if I just change the size, hit ok and then do it again to change it to 72, it will make a change to the size.
I am just trying to keep the quality as high as possible while not making the file size bigger than it used to be so that it loads faster. NO sense in having info in there if no one can see it or take advantage of it, right?

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