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I used to be color blind...

I was contacted today via private e-mail by Rafal Czlonka, as the hackergotchi I use (at least) in Planet Debian is wrongly rendreed by his WebKit-based web browser, Arora. So, in order to get more people to notice the bug if it exists: This is my hackergotchi (copied from Planet Debian, so I can update it and this post still shows a valid one):

And this is the sample he sent me on how it is rendered by Arora - Pay no attention to the horizontal lines (those are taken from the background where it is rendered):

So, is the first image correctly rendered? (I usually have my skin in a pinkish tone, and I was wearing a blue shirt). But, yes, that makes understanding the PNG encoding a bit more interesting. I guess PNG defines hues (as neither of those colors is completely uniform, they both vary slightly depending on the section of the picture)… And for some reason, my hackergotchi (generated by the Gimp) confuses the renderer and makes it switch the hue areas?

(Note that I am tempted to use the corrected version as my hackergotchi.. It looks more interesting!)

[update] I could not resist it… and have uploaded my blue hackergotchi to - Yes, I’m a smurf now, it’s no longer a rendering error.


arora.png (20 KB)

hackergotchi_2008-2009.png (11 KB)


Albert 2009-04-24 18:41:14

Looks good in Epiphany Webkit

Works for me with Epiphany Webkit, and best captcha ever!

gwolf 2009-04-24 13:46:31


…I didn’t understand in your mail that the hackergotchi was displayed fine by itself. Even stranger… That’s then not as much a bug in the PNG decoder (I guess it uses libpng much like anything else) but in Webkit. Does it always happen at planet Debian? Does it happen with the image on this post? With the hackergotchi as part of the message body in Planet Debian?

gwolf 2009-04-25 08:55:26

Don’t test on planet anymore!

..I have uploaded my blue face over there.

henzenmann 2009-04-25 01:04:36

Rendering error!

This is what it looks like on my PC!!! ;-)

Ismael 2009-06-19 12:00:00

In the Opera RSS reader the

In the Opera RSS reader the same bug occurs, your face appears blue. When opening the web page, it appears normal. Until this post I thought you went blue for some crazy reason :P

Opera info: Version 9.64 Build 2480 Platform Linux System x86_64, 2.6.29-2-amd64 Qt library 3.3.8b

Opera/9.64 (X11; Linux x86_64; U; en) Presto/2.1.1

Javi 2009-04-24 11:07:07

Hey blue man!

You look like X-Men Beast in that picture :)

I think you should fix that horizontal lines and start using it now!

ps: Your geeky captcha looks amazing.

Johannes Berg 2009-04-25 00:26:07

also borked in gtkhtml

Fun. But evolution, via gtkhtml, is also displaying you as a smurf…

Julian Andres Klode 2009-04-24 10:59:39

Works for me.

It works for me on unstable, using Arora (WebKit Qt 4.4.3-2) Midori (WebKit GTK+ 1.1.3-3) Iceweasel (Gecko

There seems to be a bug in the version of WebKit he is using (which is shipped as part of Qt).

Julian Andres Klode 2009-04-24 14:17:00

Maybe you did not understand

Maybe you did not understand me. All browsers I listed produces exactly the same result, without any problems.

See This image for an example of Arora. I verified it with Qt 4.4 (unstable) and Qt 4.5 (experimental), using CDE & GTK+ styles and everything works perfectly for me.

poli dudik 2009-04-26 13:03:00


well… knowing that you are not having easy times there… anyway, have a very happy birthday. I don’t know if u are going to be able to go to teh office, but if not… try to enjoy it at home! as it is said: al buen tiempo, buena cara! XXX poli

rjc 2009-04-24 11:04:59

PNG in Arora

I have to add though that both of the images are taken from Arora: the one on the left is how it looks like on the website, the one on the right is how it looks like “on its own” (PNG image opened in the new tab).

rjc 2009-04-24 12:25:00


I’ve mentioned to Gunnar before, that this affects Arora on Debian (QtWebKit). Midori and Kazehakase (two other WebKit-based web browsers in the repository) are unaffected. Neither is Iceweasel or Opera or other platforms for that matter (eg. Arora on Mac OS X and Windows renders it correctly). Arora + Qt were stock Debian ones (unstable).

rjc 2009-04-24 23:47:09

He shoots, he scores!

I did understand. Your screenshot allowed me to nail it down, though! As it is too big to fit into my browser window it has been scaled and some colours got all funny, eg. heads got blue, etc. I don’t know how did I miss it in the first place (I did check the planet’s markup before). Affected are only those “heads” which have “height” and “width” not set to their correct values, eg.: hackergotchi for </code> The actual size of that PNG is 69x96.

So that narrows it down a bit. Is this a PowerPC specific (or big-endian in general) bug again? Funny, as I thought I’d checked it at work as well (i386). Anyway, thanks for taking the interest.

vicm3 2009-04-24 11:05:39

The corrected version?

You say where you look like a smurf? :)