iOS Per pixel RGBA from a png or UIImage

[thisma]

Thank you

I'm trying to find the color data, most importantly the alpha, for an arbitrarily chosen point or pixel in a png I have assigned to a UIImage.
My friend and I have been searching google and the frameworks for hours with no leads.

Please help,
thisma

 

[PhoneyDeveloper]

Core Graphics. Create a bitmapcontext, draw your image into the context, read the pixels to your heart's delight.

google CGBitmapContextCreate & CGContextDrawImage

 

[kainjow]

That's for creating a new image. I think he wants to get the raw data from an existing image, which CGImageGetDataProvider() will do. See here for more info.
http://developer.apple.com/qa/qa2007/qa1509.html

 

[thisma]

That's for creating a new image. I think he wants to get the raw data from an existing image, which CGImageGetDataProvider() will do. See here for more info.
http://developer.apple.com/qa/qa2007/qa1509.html

That's probably enough for us to state making it work. I'm concerned that this will be more memory intensive than I'd like.
The main thing still remaining is, I'm a little bit of a noob and I don't see what to write to pull the data from pixel x,y. I'll read over it again though.

BTW thank you both of you.

 

[swyitch]

did you guys figure out a solution for this?

im am in desperate need of knowing how to do this, please post solution if you have one

-jeff