Saturday, November 19, 2011

Saving jpegs, the saga continues...

Sam Siciliano asked the following question...

Gary, I tried using the alternate 'save for web' rather than 'save as', but I ran into many memory issues.  I'm not exactly sure what is going on.  I'm running Windows XP, and I have about as much usable memory as possible with that OS.  I have 4G, of which about 3.2G is addressable.  Photoshop Preferences shows that it can get up to around 1.6G, and I set the level up to 1.2G, which it seems to recommend.  However, I keep getting warning messages pop up when I try to view jpegs in 'save for web' 2-up.  Forget 4-up!  If I lower the percentage (of which I'm not sure) and start shrinking what is displayed in the windows, I have better luck.

I wondered if the sheer size of my files is creating a problem.  My Sony full-frame has one of the biggest sensors available, and my raw files are around 33M.  When I save a psd file in CS5 in 16-bit mode with that Prophoto RGB color profile and with even a couple layers, I get files of about 350M!  This does seem rather huge to me.  When I was using Photoshop Elements, 8 bit, and default sRGB, my files were only around 150M.  However, I had memory issues with 'save for web' there as well.  Anyway, I'll try to bring in a file to try on the class PCs, but let me know if you have any ideas or suggestions!


You actually are asking a real good question here…


and It finally dawned on me what the "size" requester is useful for in Camera Raw.
At some point when you send photos to Photoshop you need to decide what size you require for final output. What you see in this requester depends on the camera that you are using.


You need to be careful here, as you need to choose a size that is going to give you the best print at the ppi (Pixels Per inch) that you are sending to the printer.
The larger the print the more resolution (Total megapixels needed)
Save for Web will issue a warning about size as it creates cache space for each display window…
Most .jpg files are used for display on the web. Or for Computer slideshows with images formatted for the resolution of the screen. And as a result are have a "Low" Resolution...
One of the places where you can make a resolution (size) commitment is with
Image > Image Size…
How large a resolution do you need for a "perfect" print?

Divide the width of a picture in pixels by the # of pixels per inch (PPI) --the value you told the printer to print per inch

EG from the data in the above requester

3456 pixels / 300 pixels per inch
= 11.52 inches

2304 Pixels / 300 
Pixels per inch
=7.68 inches
You can of course turn that around and calculate the # of pixels needed for say a 12 x 18 print @300 PPI
12 inches x 300 Pixels/inch  = 3600 Pixels
18 inches x 300 Pixels/inch =  5400 Pixels
To print a bigger picture you'd need either more resolution (More Mega-pixels) or print with less ppi
and, you can always change the PPI without affecting the Resolution of the image
decisions, decisions, decisions
got more questions?
as usual 'holler!


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