Image Procesing Sharpness on UIImageView with a Slider

Discussion in 'iOS Programming' started by rickjackson, May 18, 2011.

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  1. rickjackson, May 18, 2011

    rickjackson macrumors newbie

    Joined:
    Dec 24, 2010
    #1
    Hello to all,

    I am new to iPhone Development and even new to Image Processing but guyz i all of your help I am learning Image Processing in Bits and Pieces What i have learned so far is that how can i obtain the Actual pixel data from CGImage object and how to create a new modified image here is the code :

    Code:
        CGImageRef sourceImage = theImage.image.CGImage;

    CFDataRef theData;

    theData = CGDataProviderCopyData(CGImageGetDataProvider(sourceImage));
    
    UInt8 *pixelData = (UInt8 *) CFDataGetBytePtr(theData);
    
    int dataLength = CFDataGetLength(theData);
    But right now i am struck at a point how can i increase/Decrease the sharpness of UIIMageView With a Slider.

    Please share your thoughts with us so it will benefit all of us in someway.........

    Regards,
     
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  2. dantastic, May 19, 2011

    dantastic macrumors 6502a

    dantastic

    Joined:
    Jan 21, 2011
    #2
    Have a look at the sample project GLImageProcessing. I think it has what you are after.
     
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  3. rickjackson, May 19, 2011
    Last edited: May 19, 2011

    rickjackson thread starter macrumors newbie

    Joined:
    Dec 24, 2010
    #3
    Hello Dantastic thanks for your reply........

    Since i have not worked on OpenGL so its hard to understand that code but i have found this article which explains about image processing but not in detail here is the link http://www.fiveminutes.eu/iphone-image-processing if any 1 points me to some algorithm for brightness, saturation, hur, sharpness and contrast then it will be very good.
     
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  4. dantastic, May 19, 2011

    dantastic macrumors 6502a

    dantastic

    Joined:
    Jan 21, 2011
    #4
    If it's core image you want to use have a look at the Documentation. There are a few methods there to sharpen and blur an image. Pick the one that would suit your needs.

    I suggest retaining the original image at slider mid point and when values are at the lower end of the slider use a blur function and at the higher end a sharpening function. make sure to always use the original image so you don't compound the effects.
     
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  5. rickjackson, May 19, 2011

    rickjackson thread starter macrumors newbie

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    Dec 24, 2010
    #5
    Hello Dantastic I have found information about Core Image and its not available in iPhone check this link out : http://stackoverflow.com/questions/2105475/iphone-core-image-filter
     
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  6. xStep, May 19, 2011

    xStep macrumors 68000

    Joined:
    Jan 28, 2003
    Location:
    Less lost in L.A.
    #6
    CGImages are Immutable, With Exceptions?

    That link is interesting. The guy is changing a CGImage when Apple says that CGImages are immutable; here and here. I suppose since he isn't actually displaying the input image that it might be safe, but I wonder if it would have been safer to do the change by writing the altered bytes into a new image buffer that CGBitmapContextCreate() could have created for him which is rather quick. Can someone with more CG experience shed some further opinion on this please?

    Regarding the rest. A verbal discussion I was in lately suggested that since Apple doesn't supply Core Image in iOS, that you're on your own to create or find a library that does those things. In my case, I'm looking for methods to feather CG strokes in realtime.
     
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