Pixel Color Detection Possibilites...

andynick

I imagine you guys see pretty similar posts most of the time, so maybe this one will be a little more abnormal. Let's see if anyone can help me with this:

I've heard that php can work with images on a pretty crazy level - i know it can resize them and stuff, and I hear that's fairly simple.

However, i've also heard that you can use PHP to determine the color of specific pixels - is this true? I'd be very interested in writing a script that takes a small image, say 100x100 and maps the color of each pixel to an array. Any thoughts?

To be honest i'm really just looking to see if a pixel registers black or white. I can prepare the image to make sure it's either 100% black or white... where do I start? I'm eventually going to take this info and send it into flash and play from there....

anyone know how to do this? is it even possible? where do I start?

thanks all,
andy

mtmosier

where do I start?

As with most things, you start at the manual. Image functions are here. This one in particular stands out:

imagecolorat -- Get the index of the color of a pixel

andynick

aah yes, the legendary manual.

here's the thing... I don't especially know how to use php. I've coded an email script, and once used it to echo the server's date and time back to me, but I'm mainly an actionscript guy. I'd really like to figure this out though, so i'll give it a go. Basically, it looks like it's not so hard to echo this data back to me, in 1 big array, right?

am I oversimplifying this? btw, if I were to use this to loop thru an entire image, say 1 or two hundred pixels tall and wide, how long do you think this script would take to run? i'm so clueless..... thanks for putting up with me.

andy

andynick

Alright - a little bit of research later, and here I am - I need some super basic info -

http://www.boutell.com/gd/

is this what I need to begin to use this function? please please forgive my newbie-ness. It's my nature to jump into waters far too deep for my own good.

How do I use those plugins? I don't have access to my server.... can i use them locally?

andy

mtmosier

You do need to use the gd extension, but if you don't control your server it either has to be installed already, or you have to convince the admin to install it for you. To find out if you have it installed already create a script with this in it

<?php  phpinfo();  ?>

When you run it it'll tell you what modules are installed on your server, along with a lot more info. Look for the gd section.

I honestly have no idea how long it takes these functions to run. I don't do much image manipulation in php. 🙂 If I had to guess I'd think it'd be pretty fast once you have the image loaded.