PNG transparency support

[Jeff]

Is opacity on PNG images widely supported amongst mainstream browsers? I
guess that would be IE6+, any Firefox, and I'm not sure how far back to
go in Safari.

My old image editing program doesn't do transparency on PNGs.
Recommendations on free to cheap converter.

Jeff

 

[Bergamot]

Is opacity on PNG images widely supported amongst mainstream browsers?

IE6 and earlier does not support alpha transparency but handles indexed
transparency just fine, the same way as gif transparency. AFAIK, all
other modern browsers have no problem with either.

 

[Michael Fesser]

..oO(Jeff)

Is opacity on PNG images widely supported amongst mainstream browsers? I
guess that would be IE6+, any Firefox, and I'm not sure how far back to
go in Safari.

All modern browsers and IE 7 support it. The only real problem is IE 6.
Either live with that or use a workaround (just google for IE PNG fix,
there are some available).

Micha

 

[C A Upsdell]

.oO(Jeff)


All modern browsers and IE 7 support it. The only real problem is IE 6.

IE5 is also a problem, and *some* sites (e.g. the USGS site) have a lot
of IE5 users.

 

[Jeff]

IE5 is also a problem, and *some* sites (e.g. the USGS site) have a lot
of IE5 users.

No kidding? I see figures of around 1.5% for IE 5.x, and I would
think most of those would be IE 5.5 which supports the opacity filter
rewrite.

Of course, I heard of someone recently claiming to get an occasional
hit from NS4!

Jeff

 

[C A Upsdell]

No kidding? I see figures of around 1.5% for IE 5.x, and I would think
most of those would be IE 5.5 which supports the opacity filter rewrite.

I follow browser stats, and publish them. 5.01 is actually more common
than 5.5, for although 5.5 is much more capable, Microsoft has not
supported 5.5 for quite a while, whereas it does support 5.01: 5.5
therefore has a lot of uncorrected security issues, and people have
abandoned it.

For the USGS site, 17% use IE 5, mostly 5.01. This is very, very high:
much higher than most other sites. I assume that that most USGS
visitors have Windows 2000 and have not been allowed to upgrade to IE 6.

 

[rf]

For the USGS site, 17% use IE 5, mostly 5.01. This is very, very high:
much higher than most other sites. I assume that that most USGS visitors
have Windows 2000 and have not been allowed to upgrade to IE 6.

Not allowed by whom?

Are they also not allowed to upgrade from the horse and buggy?

 

[C A Upsdell]

Not allowed by whom?

The USGS site is a US government site. I think it quite likely that it
is used a great deal by bureaucratic entities -- whether government or
corporate -- which establish policies limiting what software its users
may use.

 

[Michael Fesser]

..oO(C A Upsdell)

IE5 is also a problem, and *some* sites (e.g. the USGS site) have a lot
of IE5 users.

Correct. Should have been "IE <= 6". Anyway.

But IMHO it also depends on what the PNGs are used for and if you can
live with little glitches in these old and broken browsers. Personally I
don't care that much anymore, as long as the content is accessible and
doesn't look way too bad. I only add IE fixes if _really_ necessary.

Another way to solve it besides the IE PNG hacks might be server-side
content negotiation: the server could automatically deliver the PNG to
compliant browsers and an alternative GIF or JPEG to non-PNG browsers.

Micha

 

[C A Upsdell]

.oO(C A Upsdell)


Correct. Should have been "IE <= 6". Anyway.

But IMHO it also depends on what the PNGs are used for and if you can
live with little glitches in these old and broken browsers. Personally I
don't care that much anymore, as long as the content is accessible and
doesn't look way too bad. I only add IE fixes if _really_ necessary.

Another way to solve it besides the IE PNG hacks might be server-side
content negotiation: the server could automatically deliver the PNG to
compliant browsers and an alternative GIF or JPEG to non-PNG browsers.

You can avoid a server-side solution using IE Conditional Comments.

 

[Toby A Inkster]

Is opacity on PNG images widely supported amongst mainstream browsers? I
guess that would be IE6+, any Firefox, and I'm not sure how far back to
go in Safari.

Opacity, of course; it's the transparency you need to be careful with!
;-)

Alpha blending (i.e. partially transparent areas) is supported in IE 7 for
Windows and IE 5 for Mac, though there are ActiveX hacks for IE 5.5+ for
Windows; every Gecko-based browser since mid-2000; Opera 5+ for Linux and
Opera 6+ for other platforms; all versions of Safari ever; Konqueror since
version 3.0; iCab since 1.8.

Binary transparency (a la GIF) was also supported in IE 4+ (Windows and
Mac), Opera 3.51+ and Konqueror 2.x.

--
Toby A Inkster BSc (Hons) ARCS
[Geek of HTML/SQL/Perl/PHP/Python/Apache/Linux]
[OS: Linux 2.6.17.14-mm-desktop-9mdvsmp, up 20 days, 17:39.]

Bottled Water
http://tobyinkster.co.uk/blog/2008/02/18/bottled-water/

 

[Justin E. Miller]

Use The GIMP, it can do transparencies. If you need to know how, here's
the instructions:
http://aplawrence.com/Linux/crousegif.html

 

[Raymond SCHMIT]

The free program IrfanView can do it also- easely - you choice it when
you "save as"