Photo Quality: DPI discussion continued..

[cellentani]

Ah zeolite, I was hoping you'd pop in here - thanks for all your advice! Currently, I do shoot in RAW and try to avoid as much jpeg compression as possible. I only use the sharpening feature occasionally, but I'll read up and explore that option a little more.

I agree that resizing to 640 x 480 is the best, and yes, even though PS might accept a 2MB upload, it won't display that file size.

Minous, my general rule of thumb is to capture the highest quality image possible for the camera, even though the file sizes will be larger. Get a second or bigger memory card if necessary. Resize to 640 x 480 pixels (4:3 aspect ratio) or smaller. I think there are several PSers w/ your camera model, so if you have specific issues like white balance adjustments, etc, I'm sure you could post them and get some additional help.

 

[cellentani]

Celletani, is that pendant yours? It's beautiful!

Hi pregcurious, yes, that's my pendant - it used to have a rubellite, but I dropped and chipped it a few months ago. I was lucky to find a tsavorite recently, and now I've been wearing it nearly every day. Thanks for your very kind comment!

 

[0-0-0]

thbmok wrote:
I just did my own test and it looks like PS resamples images over 480 pixels in height.

Actually, PS resamples if the longer dimension is more than 640 pixels, and it also resamples if the shorter dimension is more than 480 pixels. In thbmok 8 gemcase picture in this thread [URL='https://www.pricescope.com/community/threads/how-much-head-reflection-is-acceptable.165443/']https://www.pricescope.com/community/threads/how-much-head-reflection-is-acceptable.165443/[/URL]

the image is exactly 640x480 pixels. I determined this by downloading the PS image, and measuring image size in Photoshop.

Good catch on the 640 pixel height limit! However the original image in that case is in fact 640x480 pixels so PS did not resample.

Anyhow did a quick check on the 640 pixel height limit as well.

Original is 1200x480px, 180ppi, 391,285 bytes
PS resamples to 640x256px, 96ppi, 121,920 bytes


Original is 640x256px, 180ppi, 126,565 bytes
PS is the same


As for PNG vs JPG formats, I just want to stress that it's really important to keep images in PNG format as long as you still plan on editing the image. The JPG format may go through re-compression every time you save new edits.

 

[kenny]

FWIW, RAW files are not one standardized type of file.

Each manufacturer may have their own version of "RAW" file.
I think the only thing all RAW files have in common is they are uncompressed and huge.

I recently discovered that even Nikon changes their RAW protocol (or whatever you call it) when new body models come out.
I had a Nikon D200 body in 2007 that made RAW files that worked with that day's version of apple's iPhoto program.
I recently bought a new Nikon D7000 body and I had to wait a few months for apple to update iPhoto so it could read the D7000's RAW files.

How very annoying that was.

 

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thbmok wrote:
I just did my own test and it looks like PS resamples images over 480 pixels in height.

Actually, PS resamples if the longer dimension is more than 640 pixels, and it also resamples if the shorter dimension is more than 480 pixels. In thbmok 8 gemcase picture in this thread [URL='https://www.pricescope.com/community/threads/how-much-head-reflection-is-acceptable.165443/']https://www.pricescope.com/community/threads/how-much-head-reflection-is-acceptable.165443/[/URL]

the image is exactly 640x480 pixels. I determined this by downloading the PS image, and measuring image size in Photoshop.

Good catch on the 640 pixel height limit! However the original image in that case is in fact 640x480 pixels so PS did not resample.

Anyhow did a quick check on the 640 pixel height limit as well.

Original is 1200x480px, 180ppi, 391,285 bytes
PS resamples to 640x256px, 96ppi, 121,920 bytes


Original is 640x256px, 180ppi, 126,565 bytes
PS is the same


As for PNG vs JPG formats, I just want to stress that it's really important to keep images in PNG format as long as you still plan on editing the image. The JPG format may go through re-compression every time you save new edits.

Oops too late to edit, I meant to say 640 pixel width limit!

And I have two more images to add to the comparison to again show that the dpi/ppi setting alone is irrelevant for screen appearance.

Original is 640x256px, 1ppi, 126,565 bytes
PS is the same


Original is 1200x480px, 1ppi, 391,285 bytes
PS resamples to 640x256px, 96ppi, 121,920 bytes


The difference in the PS resampled image is more pronounced in this comparison. The prongs look noticeably softer than in the originals. So, the takeaway, as zeolite and cellentani said, is to keep images under 640 pixel width and 480 pixel height as far as uploading to PS is concerned.