iOS Image Procesing Sharpness on UIImageView with a Slider

[rickjackson]

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 :

    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,

 

[dantastic]

Have a look at the sample project GLImageProcessing. I think it has what you are after.

 

[rickjackson]

Have a look at the sample project GLImageProcessing. I think it has what you are after.

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.

 

[dantastic]

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.

 

[rickjackson]

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.

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

 

[xStep]

CGImages are Immutable, With Exceptions?

... 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.

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.