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Posted by Richard Lynch on 01/19/05 00:29
Rob Adams wrote:
> "Jason Barnett" <jason.barnett@telesuite.com> wrote in message
> news:20050118191142.432.qmail@lists.php.net...
>> Rob Adams wrote:
>>> Ok - Let me restate some of this:
>>>
>>> I am creating these images in PHP. I have a script right now that
>>> accepts two images. A main one, and the one that will be hidden.
>>> These
>>> can be either jpg, gif, or png. It then outputs a png image like this:
>>>
>>> http://imagineinc.net/images/
>>
>> By main / hidden images, do you mean blending images together? Because
>> what I saw from visiting this link was a background scenery with a
>> flower
>> etc. with red, green and blue ovals on top of it. (Firefox 1.0)
>
> I'm curious about Firefox. Did you try highlighting the image in it? If
> I
> remember correctly, Firefox's highlight grid is the reverse of Internet
> Explorers, which is what these images were made for, though I have a flag
> in
> my code to reverse my grid too. I just tried loading this in Firefox, and
> it definately doesn't have the same effect as in IE. Try it in IE, then
> highlight the image.
>
> Perhaps my example is so poor, noone here is understanding what I'm trying
> to do. Checkout this link:
> http://www.toccionline.com/creations/ctrla/
>
> That is what I'm trying to do, only with whatever two images you happen to
> want to do it with, on the fly, in PHP.
I'm assuming you've read this:
http://www.toccionline.com/creations/ctrla/how.html
The only part of that which is pretty much non-trivial would be the part
at the end about playing with the "output levels" and maybe
"brightness/contrast" until it "looks right"
You could spend the next 50 years in AI research with specializations in
visualization trying to find the perfect algorithm for that, and still
fail -- Which is about where the state of the art in AI research with
specializations in visualization is today :-)
[Apologies for this "dig" at my colleagues]
You might, however, want to do some light reading in that arena to see if
there are some simple heuristics you can "steal" to know what to do to the
image you are trying to hide.
I believe that for Firefox/Mozilla, you simply need to switch the grid
around and color-code the "other" pixels the same way, so that should be
do-able.
Bottom line, though, is that even though you are doing this in PHP, you're
basically asking a Visualization Expert question... Might as well ask us
about brain surgery, when you get right down to it. Somebody here *might*
know the answer... Sorry.
Some general principles that seem to be implied from my reading of that page:
The primary (un-hidden) image should be "busy" and not have large chunks
of all-the-same color. That makes me think JPEG might be the better
output format, though perhaps JPEG would actually muck up all the pixels
you're trying to hide in the first place...
The "hidden" image should be less busy, with larger chunks of the same
color, I suspect.
Alpha-blending the hidden image down to 50% may well prove to be a cheat
to get the desired goal for a general image.
I don't think you're EVERY going to get satisfactory results for two
randomly-selected arbitrary images. If the "hidden" image is too busy,
and the "visible" image is too not-busy, you're going to end up with the
hidden image pushing through too much.
NOTE: The entire second half of this post was all guess-work. YMMV.
--
Like Music?
http://l-i-e.com/artists.htm
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