Photoshop Elements 11 (Mac): low photo resolution in Organizer browser

dmed1  wrote Photos in browser, when clicked so that they open in full extent of Organizer window, appear blurry and pixellated on a 21" or 27" monitor. When Full Screen is selected from the View menu, the picture/s become perfectly sharp and clear. However, on re-trying since the first post, this low resolution clears after about one second per image. So I'm wondering if there is a key stroke or combination which may have been entered inadvertently to cause this.

The organizer stores thumbnails in a cache file within the catalog folder.

Those thumbnails are very small copies (max 240 x 360 pixels). Obviously, this is to enable browsing pages of many thumbnails rapidly, the organizer being an organization tool above all, and only a partial editing one (instant fix...)

When you set the slider for the zoom factor, first the thumbnail is enlarged, which is very quick but not detailed (blurry look). Depending on the speed of your computer, the original image is read again and displayed according to your setting to replace the enlarged thumbnail. Most of the time, that implies downsampling the original pixel size. Even if you choose to display a single image in the browsing space, a 6000 x 4000 pixels image will have to be reduced to much less to fit in a typical 1920 x 1200 pixels display.

The downsampling necessarily loses some detail. Even in that case, you can' see the full 100% pixels view in the browsing space. The downsampling is generally good enough for organization purposes.

When you use the full view (F11) mode, you can  not only fit each image in the whole display, but a simple click will zoom to 100% view so that one pixel in the display equals one in the original; which means that you only see a part of your image. The time to zoom to full view is short.

If you are working with big raw files (32kb for me), it takes a few seconds to read and convert the raw image with all editing settings applied. The thumbnail is updated to reflect those edits.