OpenGL was enabled before I wrote this post, I disabled it, not understanding what you wrote, then enabled it again, this time setting it to advanced. The image in my first post was at 16% zoom, if what you say works, then it shouldn't be showing as broken lines, yet it is ?
I can't explain that - OpenGL acceleration normally cleans up the resampling, making it more accurate, so that you don't see that kind of effect. Do you have Layer Styles in your document here?
Could you put up an image showing how a part of your document looks at 100% zoom?
What solution do you need?
Photoshop has never proposed to provide image detail perfection in its previews at zoom levels other than 100%. It provides, when zoomed-out, an overview facsimile of the image, intended to allow you to see how things look in total, vs. examining details. Yes, I agree even the OpenGL resampling is not doing all that good a job with this particular image. But it's because in general the resampling process is trying not to soften the image so much in your preview that you think it's fuzzy.
The previews are all optimized for speed, not quality.
I was just experimenting... Even the most sophisticated resampling techniques for display seem to do similar things with that image. It must have to do with the fact that the lines are not anti-aliased to start with, and are single-pixel width. For example, set your view zoom on Internet Explorer to 50%. It even does it on an iPad.
Your post intrigued me, so I did a little more testing.
Part of the problem, beyond just the fact that the resampling is done with a speed-optimized bi-llinear method inside OpenGL, is that the light and dark pixels appear to be being combined in gamma-corrected space - e.g., the 2.2 gamma of the display.
I compared the preview display of my own plug-ins, which do all their work behind the scenes in linear space.
My plug-in also uses OpenGL to do the resampling of one of several pre-calculated cache levels, again, all in linear space (I use a shader to bring the gamma up to 2.2 for display on the monitor as the combined pixels are output to the display).
There's more than meets the eye with Adobe's implementation... I specifically chose to use linear data for all my image operations in my implementation, because there is a quality level one can achieve with such operations that cannot be reached working directly on gamma-precompensated data. But I didn't have all the contstraints Adobe likely had, coming from some 10 prior versions that had no knowledge of OpenGL and which didn't have the luxury of manipulating high bit depth data.
Also, Adobe's cache levels (pre-downsized images, which are then fine-tuned by OpenGL resampling) likely still use their old speed-optimized CPU-based sampling methods, which threw away adjacent pixels - hence the completely dashed appearance of the 50% downsample.
This represents an area where Adobe could further improve their preview display in the future. For example, it's not hard to imagine a GPU resampling program (OpenCL or OpenGL shader) that could assist in preparing the cache levels. It's also not a really long jump to imagine an even better (Bicubic) resampling process, also GPU-accelerated. Conceivably, with today's computer power, one could imagine previews in real-time every bit as good as those provided by Image - Image Size (Bicubic) resampling.
Curiouser and curiouser...
I only see that fragmentation in my Photoshop CS6 32 bit version, while it looks better in the 64 bit version.
I suspect this is because I have optimized the cache levels differently in each. I've opted for a Cache Levels setting of 1 and OpenGL mode of Basic in my 32 bit version, because of wanting to use 16 bit layer compositing in astroimage processing, which I happened to be doing today.
Yes, I see it as even at 50%, just as you've showed above, with my 64 bit version. Here are my settings differences:
As with most things in Photoshop, it's more complex than we first imagine.