Bitmap Rasterization

jum's picture

Hi there,

I’ve experience a quite fuzzy thing: Exporting a font two times from FontLab, no known changes in the output settings.
The 1. font is the red text below, the 2. is the white text.
The only thing that was changed in between the 2. font-exports was the numbers (0 – 9) and the punctuation (,.;!?“”…) not displayed here.

It appears to be that now the Bitmaps are not the same anymore (especially the horizontal stems in a, e, s and h in the attached 300% example).
Anti-aliasing method is set to sharp in Photoshop, but this it seems has nothing to do with the different jittering in the result.

Any help or hint is highly appreciated!

Raster_Bildschirmfoto 2013-01-29.png12.54 KB
George Thomas's picture

If you are making a font and testing its quality in Photoshop, you're doing the wrong thing. Photoshop was never intended to be used for typesetting. Use a page layout program such as InDesign or an illustration program such as Illustrator to test your fonts; they don't rasterize the type.

jum's picture

Thanks for your reply, George.
In fact i do need to display the font properly in Photoshop as it is for a digital screen. The outlines still are perfectly matching – only the bitmaps are rendered differently.
I think there is something wrong with the fonts weight and therefore its final interpretation as bitmaps, still searching …

George Thomas's picture

OK, I understand what you're doing now. I come from the print world so don't deal much with screen issues, so I don't have a solution for this.

hrant's picture

The characters you added might be affecting either the vertical bounds or the hinting. If it's the former, try making the leading in Photoshop constant (although there are more robust -but trickier- fixes that can be done within FontLab); if it's the latter make sure you're not doing some auto-hinting before export (or just turn the hinting off).


jum's picture

@George No worries, prints not dead ;)
@hrant Alright, it seems its the interpretation of the vertical bounds and connected to that the hinting.
I messed a test-file up with autohinting, which worsened the effect – I will try to turn off the hinting all over.
The source of this error is not PS. The displayed font is generated digitally on a screen, so no work around possible.

jum's picture

Generally one could say, the bitmaps look terrible. When previewing the Font on a PC the numbers (PC_Preview_2013-02-04_4375.png), you get an impression of how badly the glyphs are rasterized – yet the outlines look OK. Generating Bitmap sizes for: 8, 10, 12, 23, 24, 27, 28, 32, 48, 96.

dberlow's picture

Just glad you landed safely without your heat shield burning up.

jasonc's picture

Did you say that you'd turned off hinting when generating the image embedded in your post of Fe 4 9:37am?

Because that's clearly still a hinting issue. I suppose I should ask if this is otf or ttf? I assumed otf.

aluminum's picture

I'm no expert, but I think Photoshop does its own thing when it comes to rasterizing it for the screen. Are you sure both words with set in the exact same spot in the PhotoShop file?

jum's picture

@bbg lol! (had to read this twice comparing the image)
@jasonc yes, hinting was turned off … i will try and error a couple of settings with autohinting and while exporting Preferences / TrueType/OpenType TT (.ttf) / Autohint font switched on and off. It’s .ttf with lotsa opentype features.

@aluminum Photoshop just displays the malfunction the font’s got when it comes to pixels. Could have been a possible error, but all type is set on full pixels.

jasonc's picture

@jum: note that the window you are showing us is your preferences for opening ttf fonts, not generating them. In order to turn off autohinting when generating a font, go down a few options to "Generating OpenType & TrueType",
to the subcategory "TrueType/OpenType TT", and uncheck the export hinted TrueType fonts" box.

Sorry if this is restating something you've already figured out.

Jason C

jum's picture

@jasonc ouch, you are right! anyway the font still looks crap in a windows preview.

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