Finding the edges of an image through PHP [GD]?

Xodius

This is sort of strange question, but I have no idea how to accomplish this, or if it would even be possible.

Essentially what I'd like to do it be able to feed an image in, and have a 'ascii outline' come out from it.

For example, lets say this is the source image:

Would output something like this:

[FONT=times new roman]…………………………………………………
…………………………………………………
…………………………………………………
…………………………………………………
…………….-------------------------…………….
…………….|………………….. .|…………….
…………….|………………….. .|…………….
…………….|………………….. .|…………….
…………….|………………….. .|…………….
…………….|………………….. .|…………….
…………….|………………….. .|…………….
…………….|______________|…………….
…………………………………………………
…………………………………………………
…………………………………………………
…………………………………………………
[/FONT]

If you have any insight, that would be nice.

bpat1434

What about getting the image size from gd:

$size = getimagesize(image_name);
$width = $size[0];
$height = $size[1];

From that you can deduce that the top left corner is 1,1 (x,y) through width, height (x,y). From there, you can do as you wish.

~Brett

Ravenous

I'm not familiar enough with the GD library, but assuming you can get color information at the pixel level into an array or some other representative data structure, then sure. I'm not gonna go into the method of finding edges 'cause either 1) you need to have an idea of how its done before even posting this and 2) you would then realize that edge detection is not readily explained via a post on a bulletin board.

But if you do need it explained, I guess I could try to spell it all out.

UPDATE:
So after 30 seconds of searching, I came across [man]imagecolorat[/man]. This should get you going. In fact, I just now decided to write an edge detection script myself! Thanks for the inspiration.

So yes.. edge detection is possible with PHP and the GD library. I don't know about the ASCII output, but perhaps you know what's going on there. But now the question is, which algorithms do you use?

tekky

http://www.text-image.com has a function that does images into text.... source is open, just take a look at it to get an idea of how to produce ascii output of images... 😉