iOS Per pixel RGBA from a png or UIImage

T

thisma

macrumors member

Original poster

• Sep 12, 2008

• #1

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

macrumors 68040

• Sep 12, 2008

• #2

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

google CGBitmapContextCreate & CGContextDrawImage

 

K

kainjow

Moderator emeritus

• Sep 13, 2008

• #3

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

 

T

thisma

macrumors member

Original poster

• Sep 13, 2008

• #4

kainjow said:

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

Click to expand...

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.

 

S

swyitch

macrumors newbie

• Jan 5, 2009

• #5

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