Re: Adam7 and narrow PNG

[Vladimir 'φ-coder/phcoder' Serbinenko]

On 02.10.2013 08:57, Melki Christian (consultant) wrote:
> Limited usefullness. I've used a lot of PNG's in GRUB lately and can't think 
> of a reason why I would use either.
> Maybe paletted 8-bit (if-that’s what you meant?) to save space..
8-bit palette is an easy one. The tricky one is 4-/2-/1-bit palettes
(16-/4-/2-color) since then PNG packs several pixels in a single byte.
Usefulness of it to compress image is debatable since although it saves
space by itself, it messes with filter and huffman.
> but adam7? It's still going to be loaded as a bitmap.
> If I had some web png's and was to lazy to pass them through a converter...
The compatibility is the idea. Or if editor used by artist defaults to
adam7 and doesn't have an option (at least not easily accessible one) to
change this behaviour
> That beeing said, the work is done and unless it adds rediculous ammount of 
> code size or execution time I'd be fine with the support.
> 
>> -----Original Message-----
>> From: address@hidden
>> [mailto:address@hidden On
>> Behalf Of Vladimir 'f-coder/phcoder' Serbinenko
>> Sent: den 2 oktober 2013 02:25
>> To: The development of GRUB 2
>> Subject: Adam7 and narrow PNG
>>
>> It was reported that GRUB doesn't support Adam7 and paletteed PNGs.
>> Attached patch would implement both of them but combining them results
>> in quite complex code since PNG works on bytes even if bpp <= 4 but
>> adam7 works on pixels. Does anyone have thoughts on adam7 and narrow
>> PNG usefulness?
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