Comments on: Beginning iPhone Development: Exploring the iPhone SDK http://www.matthewbull.net/2009/05/24/beginning-iphone-development-exploring-the-iphone-sdk/ web development and photography Fri, 29 Jan 2010 22:11:41 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: matthew http://www.matthewbull.net/2009/05/24/beginning-iphone-development-exploring-the-iphone-sdk/comment-page-1/#comment-316 matthew Sun, 11 Oct 2009 09:40:51 +0000 http://www.matthewbull.net/2009/05/24/beginning-iphone-development-exploring-the-iphone-sdk/#comment-316 Well, I found it tricky because I'd not done any image processing before, and hadn't even done much C programming. However this code on googlecode was helpful to get started: <a href="http://code.google.com/p/simple-iphone-image-processing/" rel="nofollow">http://code.google.com/p/simple-iphone-image-processing/</a> The code didn't seem to work as-is with colour, but with some hacking around you should be able to get it working. Basically you just have to remember that each pixel in a colour image has three 8-bit colour channels and an alpha channel, each with values between 0 and 255. So processing an image consists of looping through bytes 1-4, 5-8, etc (ie pixel by pixel), modifying the values for each byte (channel) to get the colour you want for the overall pixel. The principle is simple, but getting it right in practice is a bit fiddly. Good luck! Well, I found it tricky because I’d not done any image processing before, and hadn’t even done much C programming. However this code on googlecode was helpful to get started:
http://code.google.com/p/simple-iphone-image-processing/

The code didn’t seem to work as-is with colour, but with some hacking around you should be able to get it working.

Basically you just have to remember that each pixel in a colour image has three 8-bit colour channels and an alpha channel, each with values between 0 and 255. So processing an image consists of looping through bytes 1-4, 5-8, etc (ie pixel by pixel), modifying the values for each byte (channel) to get the colour you want for the overall pixel.

The principle is simple, but getting it right in practice is a bit fiddly.

Good luck!

]]> By: Bob Williams http://www.matthewbull.net/2009/05/24/beginning-iphone-development-exploring-the-iphone-sdk/comment-page-1/#comment-315 Bob Williams Sun, 11 Oct 2009 04:07:26 +0000 http://www.matthewbull.net/2009/05/24/beginning-iphone-development-exploring-the-iphone-sdk/#comment-315 Getting ready to start iPhone development project that will need to take a photo and then modify it. Can you give me some good reference sites to get me started. Thanks in advance Bob Williams Getting ready to start iPhone development project that will need to take a photo and then modify it. Can you give me some good reference sites to get me started.

Thanks in advance
Bob Williams

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