PNG transparency

R

Roedy Green

There seem to be at least two flavours of PNG files with transparency.

The transparency in some images does not always work, in particular in
Internet explorer and Corel Paint shop Pro.

Java generates files with this "iffy" sort of transparency.

Does anyone know what is going on?

There is a similar problem with ico file transparency, not always
honoured.

is there some sort of test/fix utility?
 
T

Tom Anderson

There seem to be at least two flavours of PNG files with transparency.

The transparency in some images does not always work, in particular in
Internet explorer and Corel Paint shop Pro.

Java generates files with this "iffy" sort of transparency.

Does anyone know what is going on?

I was looking over the PNG spec the other day, and i recall that there are
indeed two types of transparency. There's what i would consider proper
transparency, done with an alpha channel - every pixel has a transparency
value between 0% and 100%. There's also some alternative, lightweight
mechanism, where pixels are either transparent or opaque - i think it
works by defining some particular colour as being magic, and then every
pixel of that colour is taken as actually being transparent. I am a bit
vague on this - have a read of the PNG spec and you should find out; it's
a very readable spec as specs go.

I have no idea whether this has anything to do with your problem, though.
is there some sort of test/fix utility?

Not that i know of. It should be pretty simple to examine your files, with
a hex editor or some kind of PNG tool (which you might have to write - but
it wouldn't be hard, PNG is easy!), to see what kind of transparency
they're using.

tom
 
K

Knute Johnson

Roedy said:
There seem to be at least two flavours of PNG files with transparency.

The transparency in some images does not always work, in particular in
Internet explorer and Corel Paint shop Pro.

Java generates files with this "iffy" sort of transparency.

Does anyone know what is going on?

There is a similar problem with ico file transparency, not always
honoured.

is there some sort of test/fix utility?

IE through 5.0 has significant problems displaying PNG images. It
supports only binary transparency with palette based images only and the
threshold is AFU.

IE 6.0 is better but I don't have exact details for you.

I haven't seen any problems with IE 7.0.

I have played with PNG and Java some and found some problems with PNG
images that when loaded off disk are not in a compatible format. Just
use a ColorConvertOp to to get a compatible ColorSpace. In fact that
might just solve your problems.

I'll try some experiments on Java PNG transparency. If I come up with
anything I'll post it.
 
A

Andrew Thompson

...
IE through 5.0 has significant problems displaying PNG images.  It
supports only binary transparency with palette based images only and the
threshold is AFU.

American Federation of Umpires?
All f**ked up?

..Something else?
IE 6.0 is better but I don't have exact details for you.

If you have the PNGs, I have the IE6. (Considers -
OK I suppose I 'have the IE 6' even if you do not
have the PNGs, but I'm willing to throw my IE6 at
a couple of PNGs and report back.)
 
R

Roedy Green

If you have the PNGs, I have the IE6. (Considers -
OK I suppose I 'have the IE 6' even if you do not
have the PNGs, but I'm willing to throw my IE6 at
a couple of PNGs and report back.)

Please view the "doctored" and "undoctored" images at the bottom of
http://mindprod.com/applet/masker.html and tell me what you see.

I suspect doctored = mickey mouse and undoctored = alpha channel.
 
K

Knute Johnson

Roedy said:
Please view the "doctored" and "undoctored" images at the bottom of
http://mindprod.com/applet/masker.html and tell me what you see.

I suspect doctored = mickey mouse and undoctored = alpha channel.

I've got three browsers, IE 7, Firefox 3 and Opera 9 something and the
images all look exactly the same on all three. And they all appear
clean with nice anti-aliased edges to the text.

I suspect if you are seeing raggedy edges on one that that is the IE
fault of not doing the threshold correctly.
 
A

Andrew Thompson

...
Please view the "doctored" and "undoctored" ..

I am not sure what you mean by that.
..images at the bottom of http://mindprod.com/applet/masker.html and tell me what you see.

I see a page with a *lot* of PNG files!

Searching the source suggests the 'last two' are actually
<http://mindprod.com/image/seal/htmlvalidated.png>
<http://mindprod.com/image/seal/icra.png>
Both of which seem to be solid color PNG files.

OTOH, I suspect you are actually referring to..
<http://mindprod.com/image/stylesheet/totop.png>
<http://mindprod.com/image/stylesheet/home.png>
?

Both those images show a gray background in IE 6,
while the BG is transparent in FF3.

As an aside - I decided I'd leave it 'another couple
of years' before I started to use PNGs with transparency
in web pages. Perhaps by then, enough browsers will
display them properly to justify showing the rest of
the browser users potentially 'damaged' views.

..and perhaps even then I will write a 'transparent'
message in the image with words to the effect 'Your
browser is obsolete and broken. To view this page
properly, update your browser'.
 
A

Andrew Thompson

Why would children have a problem with "all flaked up"?  There's nothing bad
about "flaked".

;-)

( Though next time I'll extend the f**ked to f***ed,
just to add that element of mystery. )
 
L

Lew

(e-mail address removed) (Almond) wrote,
Roedy said:
I have been here for over a decade, contributing to the Java community
with thousands of hours of work. You are a newcomer, with a serious
homophobia problem. It has nothing to do with Java.

Almond is not a newcomer. He's been doing this kind of catchup for nanoseconds.

Otherwise you are correct.

--
Lew


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
"It isn't pollution that's harming the environment.
It's the impurities in our air and water that are doing it."

--- Adolph Bush
 
A

Andrew Thompson

You are looking for a picture.

(laconically) An URL paints a thousand words.
...The images you look for look like
ordinary text.  They are text images of my email address created by
Masker to make spam harvesting more difficult.

So, these two, I am guessing (after another 10 minutes
hunting through source and doing direct fetches)..

<http://mindprod.com/image/mailto/doctored.png>
<http://mindprod.com/image/mailto/undoctored.png>

Your suspicions were correct. IE6 shows the doctored
image with a transparent BG (gray in the web page -
white on direct fetch), but the undoctored one has a
gray BG either way.

I might look more closely over your page on transparency
in the near future. It seems the full-transparency mode
is widely enough supported to start using it on the World
Wild Web. And it saves having to use a GIF.
 
A

Almond

Roedy Green said:
Please view the "doctored" and "undoctored" images at the bottom of
http://mindprod.com/applet/masker.html and tell me what you see.

Get da **** out of here, you spamming ******,
advertizing his dildos thru Java programmer group.
Git it?
I suspect doctored = mickey mouse and undoctored = alpha channel.

You need to get fucked in the arse by the lion,
or better yet, the Elephant, you stoopid conman,
pretending to be a programmer.
 
A

Almond

Roedy Green said:
You are looking for a picture.

Sure, of a dildo for sale at a moderate price.
What else, mr. cocksucker?
The images you look for look like
ordinary text. They are text images of my email address created by
Masker to make spam harvesting more difficult.

You, stoopid ass, could not even manage to separate
the Java related pages from all the homo-degenerate
sales pitch on your site.
What are you doing here, arse?
 
L

Lew

Roedy said:
What the heck. How did "applet" get changed to "shoe"?

Perhaps we need to digitally sign messages for a while.

You have not been unwinding the saga of the "Fake Norma"?

--
Lew


- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
"When a Mason learns the key to the warrior on the
block is the proper application of the dynamo of
living power, he has learned the mystery of his
Craft. The seething energies of Lucifer are in his
hands and before he may step onward and upward,
he must prove his ability to properly apply energy."

-- Illustrious Manly P. Hall 33°
The Lost Keys of Freemasonry, page 48
Macoy Publishing and Masonic Supply Company, Inc.
Richmond, Virginia, 1976
 
R

Roedy Green

You, stoopid ass, could not even manage to separate
the Java related pages from all the homo-degenerate
sales pitch on your site.

They are quite separate sections. Obviously you found the gay
glossary interesting enough to spend enough time it to find the dildo
entry.

At some point they will be separate domains. Some advertisers freak
that the gay glossary is there.


Similarly the whole site gets blocked, ignoring the ICRA ratings.
But this has nothing to do with PNG transparency.
 
R

Roedy Green

Get da **** out of here, you spamming ******,

I have been here for over a decade, contributing to the Java community
with thousands of hours of work. You are a newcomer, with a serious
homophobia problem. It has nothing to do with Java.
 
S

Sherman Pendley

Roedy Green said:
Please view the "doctored" and "undoctored" images at the bottom of
http://mindprod.com/applet/masker.html and tell me what you see.

I suspect doctored = mickey mouse and undoctored = alpha channel.

You're correct - I loaded both into Photoshop, which says that the
doctored image is indexed (i.e. mickey mouse) color, and the other is
RGB color.

sherm--
 

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