What is RAW doing with resolution?

Hello,

I am very perplexed about this, and I will try to propose my question as clearly and straightforward as possible.

When I'm in Camera RAW (ACR) and I click on the "Workflow Options" at the bottom of the screen, I am of course presented with my options of color space, bit depth etc. Now, I can select from all sorts of image sizes from the dropdown, e.g. 1536 by 1024, 2048 by 1365, 5184 by 3456. Separately, I can also enter any resolution under the sun that I want.

So, the image size first: I am assuming that the size listed with no "-" or "+" next to it would be the camera's native/natural size. So if you select a "+" size to increase the size or a "-" to decrease, what is actually happening? Is RAW resampling the image just like you would do manually in Photoshop, using an interpolation engine?

And now the resolution (this is the part that may be hard for me to explain): I can enter any ppi amount that I want, whether it's 50 or 240 or 360 or 900. No matter what I enter, the image dimensions do not change. So would that imply no resampling? If so, how do you figure out how much variation you can introduce to the image in terms of adding or removing pixels?

RandMan wrote in post #15761647
Hello,

I am very perplexed about this, and I will try to propose my question as clearly and straightforward as possible.

When I'm in Camera RAW (ACR) and I click on the "Workflow Options" at the bottom of the screen, I am of course presented with my options of color space, bit depth etc. Now, I can select from all sorts of image sizes from the dropdown, e.g. 1536 by 1024, 2048 by 1365, 5184 by 3456. Separately, I can also enter any resolution under the sun that I want.

So, the image size first: I am assuming that the size listed with no "-" or "+" next to it would be the camera's native/natural size. So if you select a "+" size to increase the size or a "-" to decrease, what is actually happening? Is RAW resampling the image just like you would do manually in Photoshop, using an interpolation engine?

Correct; ACR is using optimized algorithms to interpolate the data and the results are the same as using Photoshop; the major difference is that Photoshop has more options for precise resampling.

Why should the image dimensions change? PPI is an instruction to your printer specifying how many pixels should be printed for each square inch. It has nothing to do with screen display or pixel dimensions.

PixelMagic wrote in post #15761730
Correct; ACR is using optimized algorithms to interpolate the data and the results are the same as using Photoshop; the major difference is that Photoshop has more options for precise resampling.

Why should the image dimensions change? PPI is an instruction to your printer specifying how many pixels should be printed for each square inch. It has nothing to do with screen display or pixel dimensions.

I might get this way way wrong, but if you "designate" the resolution in RAW yourself, then why would the following not work (unless it actually does)? This would be with the intent to print:

1) open image in Camera Raw
2) set resolution really high, to something like 600, 800, 1000
3) Output to Photoshop and do your adjustments
4) Aaahhhhhhh!!!!!!! I just got it--it all just made sense to me finally as I was typing this list.

Case closed!

RandMan wrote in post #15766195
I might get this way way wrong, but if you "designate" the resolution in RAW yourself, then why would the following not work (unless it actually does)? This would be with the intent to print:

1) open image in Camera Raw
2) set resolution really high, to something like 600, 800, 1000
3) Output to Photoshop and do your adjustments
4) Aaahhhhhhh!!!!!!! I just got it--it all just made sense to me finally as I was typing this list.

Case closed!

OK, for the sake of those who don't "get it", what is it that you "got"?