Better Photoshop display

March 24, 2006 11:15 AM

Photoshop CS2 does a terrible job scaling down an image when displaying it in the edit window. Is there an equivalent of "Bicubic" for when I'm looking at an image on screen?

I'm editing digital photos, typically 3456x2304 images. 33% zoom is a natural size to work at on my monitor but Photoshop's scaling algorithm for displaying images while editing is terrible. I get awful jaggies from any straight lines in my photos. The scaling in 50% zoom looks better, but it's too big for my monitor.

Is there some configuration option for Photoshop that says "use a better scaling algorithm for display while editing"? Sort of the equivalent of Bicubic when resizing, only just for edit purposes.

posted by Nelson to Computers & Internet (15 answers total)

Best answer: Unfortunately, no -- Photoshop uses the nearest neighbour algorithm to scale the view. The only trick that works is the scale in multiples of 2 (100%, 50%, 25% etc.) as this ensures a loss of pixels that is even across the picture. Pretty scandalous for the world's finest image-editing program.
posted by gentle at 11:32 AM on March 24, 2006

People say you can fix this by increasing your number of image cache levels in the preferences.

You can specify the number of cache levels in the Preferences>Image & Memory Cache screen (Figure 4). Needless to say, the higher the number of cache levels, the more resources Photoshop needs to consume. If you have limited RAM, or scratch disk space, you may wish to set the level to 1 or 2; the default is 4 levels. You can go as high as 8 levels, which will give you cached views at 66.67, 50, 33.33, 25, 16.67, 12.5, 8.33, and 6.25%. Setting the cache level to 1 is the same as turning it off because only the current view is cached at that setting.

But I tried it, and I didn't see any difference at all.
posted by designbot at 11:45 AM on March 24, 2006

gentle is correct, it's all about the even multiples. This is all about speed, it would be scandalously slow otherwise.
posted by doctor_negative at 12:20 PM on March 24, 2006

If PShop used the GPU to do screen scaling, I don't think it would be scandalously slow.
posted by Good Brain at 1:07 PM on March 24, 2006

Zooming in, you probably don't want bicubic interpolation, you want big blocky pixels that you can tweak individually.

Zooming out, you probably don't want bicubic interpolation, you want some kind of averaging. If I'm viewing at 10%, bicubic interpolation means only 16% of the pixels (4x4 out of 10x10) contribute to the output! Still will look ugly.

Correctly downscaling a large image can be fairly slow, but I think the real reason they don't do it live is not the downsampling part of it, but the fact that that would require the full image to be rendered each time it is drawn!

As it does it now, it only has to render the number of pixels visible in the window, no matter how big your image is. Given that Photoshop is largely inteneded for print-use, actual images will often be MUCH MUCH larger than your screen.

Switch back and forth between 25% and 50% I guess is my only advice to you.
posted by aubilenon at 1:25 PM on March 24, 2006

A GPU can't operate on images that large.
posted by Steven C. Den Beste at 1:26 PM on March 24, 2006

Best answer: I had the same frustration when I first encountered Photoshop. Now I just work at 12.5, 25 or 50, using keyboard shortcuts to get around. Ctrl (Command) and = zooms in, Ctrl (Command) and - zooms out, and Ctrl (Command) and 0 zooms to such a level as to fit the entire image on screen. Spacebar turns the cursor to a Hand tool for dragging your way around.

Now things may be very different for you (and you may know all this already - if so, sorry), but I find myself saving a lot of time using Ctrl+0 to see the whole picture, hitting z to set the tool to the Magnifying Glass, and quickly dragging a box round the area I want to see. Often, I'll then Ctrl + =/- to get to a crisp zoom percentage.
posted by godawful at 2:05 PM on March 24, 2006

"A GPU can't operate on images that large"

That's arguable.

Apple's Aperture, uses the GPU pixelshader units to accelerate the processing of raw sensor data from digicams, including the 16.7 Mpixel images from a Canon EOS 1d.

6XXX series Nvidia CPUs can support 4k by 4k texture sizes. ATI looks like they may still be at 2k by 2k, but I'm not convinced that multiple textures couldn't be tiled.
posted by Good Brain at 5:11 PM on March 24, 2006

The best way to deal with this is to zoom to the view you want and then shrink or enlarge it using cmd+ and cmd- (apple) or ctrl + and ctrl - (windows).

This will 'snap' the view to the nearest multiple-of-two view which will look nice. I use this every time I zoom.

And, yes, it sucks. I am hopeful this is one of the things they will fix in CS3 (along with the deplorable display of images in Bridge, which I'm told by an Adobe insider is due to caching the images as low-quality jpegs).
posted by unSane at 5:24 PM on March 24, 2006

You'll stop noticing this after using Photoshop for ten years or so.
posted by kindall at 5:28 PM on March 24, 2006

One workaround would be to enlarge your image to 133% its actual size. This will give you the same view of the image at 25% you are now getting at 33%, which I'm guessing is where the image fills the screen.

In other words, if you transform your 3456x2304 up to 4608x3072, then you'll be able to work at 25%, viewing the same area but hopefully much better looking.

The big drawback being that you've scaled things up by a non-factor of two, and at 100% things might not be quite what they used to be. Scaling back down (transforming to 75% width/height) once you're finished working may go some way towards fixing this...ask an expert or test it; I can't run CS2 on this machine.
posted by cps at 6:58 PM on March 24, 2006

as an addendum, perhaps I should state this more clearly: the workaround I describe entails messing with the original pixels, i.e. probably a loss of fidelity. Not sure how bad it is since we're scaling up, but still, not ideal by a long shot.
posted by cps at 7:01 PM on March 24, 2006

I think kindall should get a "Best Answer."

The other option would be to get a bigger (or smaller) monitor. This is not snarky. I have dual monitors, a 19 and a 17. The 17 is better quality, and therefor I set the tones on my 17 but I work zoomed in on my 19. On my 17 12.5 is just right. I spend a lot of time zooming back and forth, and shifting the image from monitor to monitor, but it works for me (9.5 years with photoshop! (PS4)).
posted by johngumbo at 8:12 PM on March 24, 2006

Response by poster: Thanks for all the advice and some of the wacky suggestions. The answer appears to be "no, you can't make Photoshop display better" which is disappointing, but there it is.

I've got plenty of screen btw; a 1920x1200 and a 1200x1600. Turns out I can just barely get my photos on the 1920x1200 at 50% if I put all the UI on the second monitor and use the 'F' key to select a Photoshop full screen mode. I'm not wild about working that way, but at least I can see the whole photo at 50%.
posted by Nelson at 8:42 PM on March 24, 2006

Do it on one screen. In fullscreen mode, you can use the [tab] key to display/hide the toolbox and palettes.

Hovering over a tool shows the keyboard shortcut (for many-in-one tools, shift+key cycles through them). Learn the top three or four you use all the time to start, then learn the top three or four menu shortcuts you use. You can get used to working fullscreen fulltime pretty quickly.
posted by cps at 11:14 AM on March 25, 2006