Re: [png-mng-misc] A little design flaw

[Greg R. <ne...@po...>]

>> That means that it is impossible to specify the resolution value
>> of a real-world device without losing some precision, because 1m
>> obviously cannot be divided by 25.4mm without a remainder.

> Bear in mind that pHYs describes the (nominal) size of the image - it's not
> related to any real device characteristics.  This is not normally something
> where any great precision is useful - indeed pHYs as I interpret it is the
> nominal size that the image should be displayed at on a 'standard' piece of
> paper - i.e. US letter or A4.  The precision in the size of a piece of paper
> is, well, almost non-existent...

...and while physical printers undoubtedly have better precision, would
you (or anyone) notice if there were an extra pixel on a 10" page?  The
pHYs chunk still has four times that level of precision at 600 dpi
(23622 dpm), and even at one of the two most common "screen" resolutions
(72 dpi), pHYs has better than 0.05% resolution (2835 dpm).

Also, I don't believe anyone has ever requested an inches unit.  I wouldn't
be opposed to adding it, but it would be nice to know that more than one
person would find it useful (or two, if you count whoever made the bogus
valid-HTML-4.01 button at W3C:  http://www.w3.org/Icons/valid-html401.png
...Chris?).

Greg