On Sun, 20 Mar 2005, Dik Takken wrote:

> >     My experience has been to use no lines thinner than 4 pixels, preferably
> >     6 pixel and to use a bold or semi-bold sans serif font.
> 
> So that reduces the safely usable resolution down to 144 vertical PAL 
> pixels? I know I have seen plenty of TV commercials that contain still 

        No, it reduces the usable resolution down to 144 vertical *lines* 
        each 4 pixels tall.   Well, a bit less since there will be some space
        between the lines ;)

> pictures with serif fonts and lines that look very sharp (sharper than 
> the 144 pixel res allows, I think), and yet they do not flicker, at least 
> not noticeably. How do they do that?

        My hunch is that they carefully selected a font size that made sure
        no lines were less than 4 pixels.

> ...movies often do contain serif fonts (during the introduction of the movie 
> for instance), small fonts and logo's with thin lines in them (end 
> credits). All of these things look detailed and quite flicker-free on a TV 

        I think the font and pointsize are carefully chosen to minimize the
        flickering problem.  

        An interesting experiment would be to extract some stills from a DVD
        and examine the images with the GIMP or other tool and see how many
        pixels the characters take.

        Cheers,
        Steven Schultz



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