Adobe Photoshop CS5 and Photoshop CS5 Extended White Paper

Ric Grupe

Adobe® Photoshop® CS5 performance

Richard

Thanks for the link, Ric. Some of it was new to me. One thing has me scratching my head, though:

From the Optimize image files section

• Minimize print resolution—Keep your image to the optimal minimum size for the output device, ranging
from 72dpi for screen display to 600dpi for high-quality laser printing. Never use a resolution higher than the
printing device is capable of outputting.

I always thought resolution was an attribute of the output device had no effect on file size.

Perhaps what they mean is that you will reduce file sizes if you resize for the intended output dimensions and device. While I suppose that's true, I remember hearing that pro labs do a better job of resizing than PS and it's best to leave it to the printers.

colourbox

I think the resolution deal is because you can actually have too much of it these days. If you are printing an 8x10 at 300 dpi, you only need 2400x3000 pixels. That's just 7.2 megapixels. There are phones that are blowing past that these days. If you keep all the pixels from like a 5D MkII, you're expending more RAM, CPU, and disk space than you need for an 8x10. Now, of course, it's not an issue for anyone who has a loaded current machine, but I can tell you that on my own aging hardware I can notice the difference between editing a raw file from my 8MP Rebel and my 18MP 7D, to the point where if I think a shoot is just for fun and not for pro use, I will grab the 8MP camera just to not warehouse so many pixels I don't care about, because the edits will go faster.

It's a big problem with scanners too. Scanner resolution is so high now that some people leave it on max res 16-bit, and the files are just unwieldy to edit. So not editing more pixels than you need is definitely a performance enhancer.

Richard

I'm also on an aging machine, which I'm in no hurry to replace, so I understand your point. Still, I expect to have a more capable one in a year or two. I also believe that in the long term we are going to see significant improvement in output devices, which have not kept pace with either capture or processing. I would be reluctant to trade short-term performance for long-term quality.

colourbox

I should clarify a little that I don't think someone should throw out raw files. Those are compact, actually. But once you turn it into a space-hogging layered TIFF, I can see not working at it at any more resolution than you need for a job, especially if it's a one-off job like a poster or book. Master images you want maximum quality from later, yes, maintain maximum specs. It sounds like the Adobe doc is a little hardline on it by starting that last sentence "Never use...", they make it sound like it's a hard and fast rule when I agree with you that it isn't.

pathfinder

Richard wrote: »

Thanks for the link, Ric. Some of it was new to me. One thing has me scratching my head, though:

From the Optimize image files section


I always thought resolution was an attribute of the output device had no effect on file size.

Perhaps what they mean is that you will reduce file sizes if you resize for the intended output dimensions and device. While I suppose that's true, I remember hearing that pro labs do a better job of resizing than PS and it's best to leave it to the printers.

Richard, I think they are saying you do not want more pixels per inch in your digital image file, than the native output dots per inch of the printer, which for an inkjet is typically 1440 or 2880 dots per inch( at least on my Epson. )

Typically each single image pixel is actually composed of 5-10 dots of ink on the printed page.

Now if your image ( digital file ) has more pixels than the output resolution ( in dpi ) then much of the file information will be discarded on the way to the paper by the printer at is renders each pixel into dots per inch.