What's wrong with JPEG or PNG?
JPEG is evil (because it uses Evil Lossy Compression)
and should never be used under any circumstances, but
extra-especially it should never be used for images
containing text. (Yes, it is _possible_ to create
lossless JPEG images, in theory, but most image
software does not give the user that option. The
Gimp does though, I think.)
PNG is great, and has pretty much taken over as the
image format I use for almost everything (except when
I want to preserve layers...), but for the type of
images represented here (only one foreground color
in some of them...)
GIF gets better compression. Granted, the
circumstances under which it is appropriate to use
images with such a low colour depth are rapidly
diminishing; the cost of colour printers and inks
is at this point such that it might even be sensible
to have true-colour letterheads; nevertheless, there
*are* still applications for images with fewer than
256 colours. One of the best examples would be
images intended to be placed on a quantity of
t-shirts and sold or given away at a conference,
which is roughly what these images look like they
might be destined for.
$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
| [reply]
[d/l] |
Strange that you mention GIF but don't call it evil.
Reducing a general image to GIF format is usually far
more lossy than compressing it as JPEG, due to GIF only
having at most 256 colours. Furthermore, GIF is evil due
to its licensing. The announcement of Unisys to start
charging for the production of GIF is what caused PNG to
be created. PNG is a replacement for GIF - not for JPEG.
JPEG itself isn't evil. The lossy compression is usually
not something you notice, as long as you stick to the domain
JPEG was invented for: pictures. GIF and PNG shine where
JPEG doesn't: images with a low number of colours, images
with sharp boundaries between very different colours, etc.
So, typically things as drawings, icons, plots, etc.
Abigail
| [reply] |
Strange that you mention GIF but don't call it evil. Reducing a general image to GIF format is usually far more lossy
I agree with this, for general-purpose images. I would
never, for example, use GIF for icons or wallpaper or
photographs.
Furthermore, GIF is evil due to its licensing.
If the licensing were enforced in anything similar to
the fashion that was briefly threatened, I would agree.
As it stands, in practice, the licensing issues around
GIF are a minor caveat, nothing like the horrific issue
that is JPEG compression.
PNG is a replacement for GIF - not for JPEG.
No, PNG is a replacement for both GIF and JPEG, as
well as TIFF, BMP, XPM, PCX, and so on and so forth.
The only other image formats we still need besides
PNG are more advanced formats (that support things
like layers (XCF) or color-selective opacity, vector
formats (POV, SVG, and so forth), and of course the
venerable text/plain format for ASCII graphics, which
gets better compression than all the others.
JPEG itself isn't evil.
The use of JPEG lossy compression is evil. Lossless
JPEGs aren't evil, but with wide PNG support these
days (wide if you don't need the alpha channel, which
JPEG doesn't have anyway), they're rather pointless.
The lossy compression is usually not something you notice
Notice? NOTICE? It's not a question
of noticing. It's a question of being able to suppress
my negative reaction long enough to look at the image.
When an image (any image, except maybe a solid block
of exactly one colour, though of course it's worst for
text) is compressed lossily, the
compression distortion stands out as *the* predominant
feature of the image. It is the first
thing I notice. It stands out and calls attention to
itself and cannot be ignored.
$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/
| [reply]
[d/l] |
