The developer of this, Joseph Scheuhammer says:
“GNOME Shell has a built-in magnification feature. In addition to magnification, some low-vision users prefer to invert the lightness (“inverse video”), change the overall brightness, change the contrast, and/or some combination thereof“.
Also Joseph explains the reasons that this feature didn’t make it on 320 and 340.
“The work on this feature is done, and in fact demo versions were made. The initial plan was to release it as part of GNOME 3.2, but delayed when the bright-contrast-inverse Clutter effects were moved from custom code in GNOME Shell to Clutter itself. During the 3.4 cycle the algorithms were discussed and improved; and it was suggested the inverse effect should be moved back to GNOME Shell. Thus the work was not completed in time for 3.4.”
Below are the demo versions that had proposed on 320
Figure shows the lightness inversion effect. The bottom half of the screen is magnified and inverted. Note that the hues are the same (blue remains blue, orange is orange, etc.), but lightness is inverted. Compare the two views of the triangle in the colour picker, especially the left edge: Darker reds are lighter, lighter reds are darker, and grey levels are inverted.
Figure shows the a +25 per cent increase in contrast. The bottom half of the image shows the enhanced contrast view.
Most of the patches are completed and awaiting review, so we will definitely get these features in Gnome 360