P: Inaccurate selections with Radeon graphics cards on Mac OS

I can reproduce this. It's a little more subtle with OGL off but it definitely occurs with OGL on and off. Thanks for the demo video, Collin. I'll log a bug report on this.

Hi Chris,

I'm using a 2.66 GHz Late 2009 Quad Core i5 27" iMac (iMac11,1) with an ATI Radeon HD 4850 (512 MB) GPU.

Possibly related, I encounter this bug with Photoshop's "Enable OpenGL Drawing" turned off under Preferences -> Performance. With OpenGL drawing turned on, both the in-progress creation *and* completed selection don't match my cursor positions exactly. I typically turn off OpenGL drawing because it decreases marquee selection accuracy, and did so even before this Lion & CS5+ bug manifested. The two may be related, though. It would definitely be worth looking into. I can create another screencap with OpenGL turned on, if needed.

Thanks!

What machine are you using, and what video card/chip? We've seen that bug before and it was specific to certain GPU versions (ie: a bug in the driver).

Hi Michael,

The issue occurs for me under both CS5 and CS5.5 only at 100% zoom. (Higher zoom levels seem to have accurate selections, and lower zoom levels are ambiguous). It occurs with a freehand rectangle selection as well as Fixed Size selections.

Here's a quick video of the bug in action:
http://static.command-tab.com/temp/bu...
In all cases, I was careful to create a selection at 100% zoom that was *dead on* matching the blue square. Yet, when I released the mouse button to confirm my selection, it jumped and missed my carefully-aimed target by a pixel. More often than not, it misses by moving my whole selection up or by just raising the bottom edge of my selection by one pixel.

For someone who does pixel accurate work, it's frustrating to have to make a selection two, three, four times or more to get the size to "stick".

Hi,

Does this occur only with dragging out a marquee by hand, or also when using the Fixed Size option in the marquee tool options bar?

Does this occur only at certain zoom levels? Can you reproduce this problem at 100% zoom level?

Thanks

I have this problem, too, and it's made doing accurate UI work with Photoshop utterly maddening.

Potentially related, selections were also off pre-Lion when using OpenGL rendering. Disabling OpenGL and restarting Photoshop fixed the selection issue pre-Lion, but the issue is there in Lion with or without OpenGL.