JPG or PNG?

[rf]

You said that JPEG should always be used over PNG. Mind explaining how
that can not include line drawings?

Being the "another poster" I would like to know that as well

I do suspect (hope) that the Doormouse meant "use jpeg over png for pictures
but use gif for line drawings or anything else that will not tolerate lossy
compression, like images of text (logos etc).".

 

[The Doormouse]

If you're avoiding SVG by itself, you need to output to a raster image
format.

No, I just need to provide a raster image as backup in case the SVG does
not display. That, of course, has its own issues (Embed vs. Object).

The Doormouse

 

[The Doormouse]

I do suspect (hope) that the Doormouse meant "use jpeg over png for
pictures but use gif for line drawings or anything else that will not
tolerate lossy compression, like images of text (logos etc).".

Yes.

Also, "use SVG occasionally".



The Doormouse

 

[Leif K-Brooks]

No, I just need to provide a raster image as backup in case the SVG does
not display. That, of course, has its own issues (Embed vs. Object).

You're providing backup for something that's guaranteed to fail in all
four major browsers (Mozilla/Firefox, IE, Opera, Konqueror/Safari) which
don't have something extra installed? Why not provide the raster and
skip the SVG?

But even if you're just using a raster image for backup, which format
you choose would be fairly important.

 

[The Doormouse]

Why not provide the raster and skip the SVG?

Those with the plugin will benefit from the better graphics.

But even if you're just using a raster image for backup, which format
you choose would be fairly important.

True - GIF would be ideal for line art.

The Doormouse

 

[Leif K-Brooks]

True - GIF would be ideal for line art.

So you don't care about true color? Alpha transparency? Don't you even
care about bandwidth costs?

 

[The Doormouse]

So you don't care about true color? Alpha transparency? Don't you even
care about bandwidth costs?

True color for line art is not a consideration - if you need better than
255 colors for line art, you are then looking at something with a
gradient or photo. You will either end up dithering or going to JPG. PNG-
8 is not suitable for gradient images. PNG-24 is larger than JPG. JPG may
be lossy, but at high quality settings not only will this not be a
concern but also the file size will be much smaller. For archival
purposes, one can always use TIFF or PSD.

Alpha Transparency is fine for the browsers that support it, but in
practice IE does NOT right out of the box. Generally, there are few uses
for it, anyways.

Do not think that I will continue if you ask truly dumb questions like
"Do I care about bandwidth costs?". Of course I do - that's why I use GIF
for line art and JPG for photos and SVG/SWF for vector art. Why would I
even entertain a discussion on the PNG format if I was not hoping that
you would be right?

This discussion has been educational overall.

The Doormouse

 

[Chris Morris]

It depends what kind of image you have. If it's a diagram or cartoon --
that is, something with areas of entirely solid color -- then PNG is
the best format. If it's a photo or something else with lots of smooth
color changes, JPEG is better.

GIF is good for the same kind of image as PNG, but PNG should always
be used instead because PNGs are smaller and unpatented.

*Usually* smaller. GIFs tend to be smaller for images with <=16
colours and moderate to small physical dimensions, assuming both are
optimised heavily. I tend to try both formats and use the smallest.

 

[Sam Hughes]

*Usually* smaller. GIFs tend to be smaller for images with <=16
colours and moderate to small physical dimensions, assuming both are
optimised heavily. I tend to try both formats and use the smallest.

I have found PNG to be smaller even in those situations, if saved
correctly.

 

[Guest]

The basic problem is that there is no compelling reason to switch to
[PNG].

Toby, you forgot the main reason why I switched from GIF to PNG - no
patented algorithm for compressing the data! Compuserve started to assert
its patent on the LZH algorithm used in GIF. This was the very reason
that the Open Source community got together to create the PNG.

La'ie Techie

 

[Toby Inkster]

Toby, you forgot the main reason why I switched from GIF to PNG - no
patented algorithm for compressing the data!

The patent expired about a year ago.

Compuserve started to assert its patent on the LZH algorithm used in GIF.

No it didn't. Firstly, LZW is used in GIF, not LZH. And secondly,
Compuserve never held a patent on LZW. Unisys held a patent on LZW and
started to assert it. Compuserve are a nice ISP that distribute a
Gecko-based browser. Don't bad-mouth Compuserve.

 

[Aquila Deus]

It depends what kind of image you have. If it's a diagram or cartoon --
that is, something with areas of entirely solid color -- then PNG is the
best format. If it's a photo or something else with lots of smooth color
changes, JPEG is better.

GIF is good for the same kind of image as PNG, but PNG should always be
used instead because PNGs are smaller and unpatented.

PNG cannot be used if you want transparency, because the damned IE
doesn't support it

 

[rf]

Aquila Deus

PNG cannot be used if you want transparency, because the damned IE
doesn't support it

There is a quite simple (albiet verbose) hack to cause IE honor trasparency.
Search the archive, it has been mentioned several times this week.

 

[Toby Inkster]

There is a quite simple (albiet verbose) hack to cause IE honor trasparency.

Though no hacks are required if you want to stick to 256 colours with
binary transparency -- IE handles that sort of transparent PNG just fine.

 

[Aquila Deus]

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Yes, that's true. Yet it is superior for line art.

ummm... how about just use flash?

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[The Doormouse]

ummm... how about just use flash?

Well, Illy CS can output Flash.
I suppose that I could ...

The Doormouse

 

[Aquila Deus]

Though no hacks are required if you want to stick to 256 colours with
binary transparency -- IE handles that sort of transparent PNG just fine.

thanks!

 

[Aquila Deus]

Though no hacks are required if you want to stick to 256 colours with
binary transparency -- IE handles that sort of transparent PNG just fine.

thanks!