What does the ClearType setup dialog do

The ClearType font settings dialog under Windows is pictoral only. It presents a number of text renderings without ever explaining what they mean, leading to suboptimal choices. An explanation follows.

• Step 0 is a checkbox asking whether to activate ClearType at all. If disabled, fonts will be rendered with the traditional renderer, in which you get grayscale antialiasing, as well as use of embedded bitmaps (if so available in a font) when the text is non-bold 10pt or less.
• Step 1 is for the sub-pixel arrangement of the monitor. A two-way choice is offered: Horizontal RGB, or Horizontal BGR. Windows does not know about Vertical RGB or Vertical BGR like Linux/FreeType does.
• Step 2 is for the gamma value for rendering. A 6-way choice is offered and, judging by eye, they correspond to roughly FreeType's γ=0.8, 1.0, 1.2, 1.4, 1.6, 1.8.
• Step 3 is for a (de)saturation filter. A 3-way choice is offered: no reduction, 50%, 100% reduction in saturation (colorfulness).
• Step 4 is for a contrast/sharpness filter for color-capable contexts. A 6-way choice is offered: 0, 20, 40, 60, 80, 100 (no particular unit). The previous filter is already applied in the six examples, so if you set 100% desaturation, all 6 panels feature only grayscale.
• Step 5 is for a contrast/sharpness filter for monochrome-only contexts. (I do not know when that is going to get used in practice, but whatever.) Again, a 6-way choice is offered: 0, 20, 40, 60, 80, 100. If you chose 100% desaturation, step 5 is indistinguishable from step 4.

If you enable ClearType, embedded bitmaps will be turned off. Enabling ClearType and using 100% desaturation is thus a way to get good ol' antialiasing without color fringing and without the thin glyph look of embedded bitmaps.

Posted 2024-11-21 23:11 / Tags: Fonts, Windows. / link

Notes on photo sphere/panoramic EXIF metadata

• Google's EXIF/XMP metadata tag specification for panoramic images
• Panorama images with sky are to have a negative value for the CroppedAreaTopPixels tag. (The panoramic viewer of Facebook ignores the value altogether, though, and assumes the horizon in the middle of the picture.)
• If a camera or software normally produces panoramic images with cylindrical projection, then doing a vertical capture actually produces a transverse cylindrical image. There is no standardized value for the EXIF ProjectionType field to cover this. (One option is to reproject them to equirectangular — which, again, is not very well supported.)
• Facebook's document on what tags to set
• The Facebook web interface insists that FullPanoHeightPixels be half the size of FullPanoWidthPixels. Else you get “no new photos were uploaded”.

/ Tags: Photo.