AlphaImageLoader Filter problem

[CrackWilding]

This might not the best place for this, but what the heck. I've got a
page that has a bunch of 24-bit PNG files with transparency. For IE I'm
using the AlphaImageLoader filter to get around it's limitations with
the format. I've been doing this for about a year, having seen Google
successfully deploy the solution with Google Maps, and I've never had
any problems with it.

Well, now I've got a client that's having a problem. Some (not all,
oddly) of the PNGs on his website are displaying with a bunch of black
stuff on top, like a censor went over them with a black marker.
Transparent PNGs do this when printing sometimes, but I've never seen
it onscreen. The client is using IE6 on Windows XP. So I checked half a
dozen computers with the same setup and haven't been able to reproduce
the problem.

The only difference I can detect is that he's using a Comcast
co-branded copy of IE. I suspect that Comcast may have damaged
something... who knows?

Any thoughts? I can't post the site, unfortunately, but I've posted a
screenshot of the problem here:

http://saltydogdesign.com/usenet/blackstuff.jpg

Cheers,
cw

 

[Neredbojias]

To further the education of mankind, "CrackWilding"

This might not the best place for this, but what the heck. I've got a
page that has a bunch of 24-bit PNG files with transparency. For IE I'm
using the AlphaImageLoader filter to get around it's limitations with
the format. I've been doing this for about a year, having seen Google
successfully deploy the solution with Google Maps, and I've never had
any problems with it.

Well, now I've got a client that's having a problem. Some (not all,
oddly) of the PNGs on his website are displaying with a bunch of black
stuff on top, like a censor went over them with a black marker.
Transparent PNGs do this when printing sometimes, but I've never seen
it onscreen. The client is using IE6 on Windows XP. So I checked half a
dozen computers with the same setup and haven't been able to reproduce
the problem.

The only difference I can detect is that he's using a Comcast
co-branded copy of IE. I suspect that Comcast may have damaged
something... who knows?

Any thoughts? I can't post the site, unfortunately, but I've posted a
screenshot of the problem here:

http://saltydogdesign.com/usenet/blackstuff.jpg

Have client try a different browser...?

 

[Jim Higson]

This might not the best place for this, but what the heck. I've got a
page that has a bunch of 24-bit PNG files with transparency. For IE I'm
using the AlphaImageLoader filter to get around it's limitations with
the format. I've been doing this for about a year, having seen Google
successfully deploy the solution with Google Maps, and I've never had
any problems with it.

Well, now I've got a client that's having a problem. Some (not all,
oddly) of the PNGs on his website are displaying with a bunch of black
stuff on top, like a censor went over them with a black marker.
Transparent PNGs do this when printing sometimes, but I've never seen
it onscreen. The client is using IE6 on Windows XP. So I checked half a
dozen computers with the same setup and haven't been able to reproduce
the problem.

The only difference I can detect is that he's using a Comcast
co-branded copy of IE. I suspect that Comcast may have damaged
something... who knows?

Any thoughts? I can't post the site, unfortunately, but I've posted a
screenshot of the problem here:

A few ideas:

1) The PNGs are indexed (paletised) - IE can't do transparent, indexed PNGs
even with the AlphaImageLoader hack.

2) IIRC, AlphaImageLoader has some hardware transparency stuff built in
(could be wrong on this point), if this is so, perhaps it is a video card
or drivers issue. I've seen bad graphics hardware cause similar problems in
games.

Good luck. Personally, I'd just ask the client to use a proper browser.

 

[CrackWilding]

1) The PNGs are indexed (paletised) - IE can't do transparent, indexed PNGs

even with the AlphaImageLoader hack.

Nope, they're 24-bit.

2) IIRC, AlphaImageLoader has some hardware transparency stuff built in
(could be wrong on this point), if this is so, perhaps it is a video card
or drivers issue. I've seen bad graphics hardware cause similar problems in
games.

Yeah, that's kinda what I was thinking. It looks a bit like a display
driver problem.

Good luck. Personally, I'd just ask the client to use a proper browser.

Well, an odd development has occurred. Today the guy loaded up the site
and said it looks fine. So... go figure. Maybe he patched his video
drivers or something.

Anyway, thanks for the response.

cw

 

[Toby Inkster]

1) The PNGs are indexed (paletised) - IE can't do transparent, indexed PNGs
even with the AlphaImageLoader hack.

No - quite the opposite. IE *can* do transparent, indexed PNGs, even
*without* the AlphaImageLoader hack.

 

[Jim Higson]

No - quite the opposite. IE *can* do transparent, indexed PNGs, even
*without* the AlphaImageLoader hack.

No it can't. At least, not properly.

It can do indexed, transparent PNGs with binary transparency (each pixel
either shown or not) but not an image using a proper RGBA palette. Even
with an AlphaImageLoader hack it just shows them using binary transparency.

I can post an example if you like.

 

[Jim Higson]

No it can't. At least, not properly.

It can do indexed, transparent PNGs with binary transparency (each pixel
either shown or not) but not an image using a proper RGBA palette. Even
with an AlphaImageLoader hack it just shows them using binary
transparency.

I can post an example if you like.

Ok, here's a good example: take a look at:

http://surfcore.co.uk/user/1

See how in IE the shadow on the avitar is missing in IE but shown in every
other browser? I let this pass because it still doesn't look too bad and I
think the trade off for the smaller file size is worth it.

If you know a way it can be shown properly in IE without converting the
image to 32-bit, please let me know!

Also, if anyone can test how it looks in IE7 I'd be very interested in the
result.

 

[Frank Olieu]

Jim Higson wrote:
Ok, here's a good example: take a look at:

http://surfcore.co.uk/user/1

Shows *no* images in IE6. IE7 looks OK at first, but on mouse-over I get a
hatched background...

Not quite sure it applies to your case, but try have a look at
http://koivi.com/ie-png-transparency/

 

[Toby Inkster]

It can do indexed, transparent PNGs with binary transparency (each pixel
either shown or not) but not an image using a proper RGBA palette.

Ah -- I was referring to indexed PNGs with binary transparency.