Adjust image in Windows Phone 8.1

Question

I want to adjust the contrast of an image in Windows Phone 8.1 I have found samples for Windows Phone 7 but it does not work in Windows Phone 8.1.

This is my code:

    public static WriteableBitmap ChangeContrast(WriteableBitmap Bitmap,
                                                    int[] orgPixels,
                                                    double contrastValue)
    {
        var result = new WriteableBitmap(Bitmap.PixelWidth, Bitmap.PixelHeight);
        var contrastFactor = (50f + contrastValue) / 50f;
        contrastFactor *= contrastFactor;
        var contrastFactorIndex = (int)(contrastFactor * 32768);
        var inputPixels = Bitmap.PixelBuffer;
        int[] tempPixels = new int[Bitmap.PixelBuffer.Length];
        orgPixels.CopyTo(tempPixels, 0);
        if (0 != Bitmap.PixelBuffer.Length)
        {
            for (int index = 0; index < Bitmap.PixelBuffer.Length; index++)
            {
                // Extract color components
                var color = tempPixels[index];
                var alpha = (byte)(color >> 24);
                var red = (byte)(color >> 16);
                var green = (byte)(color >> 8);
                var blue = (byte)(color);
                int ri = red - 128;
                int gi = green - 128;
                int bi = blue - 128;

                // Multiply contrast factor
                ri = (ri * contrastFactorIndex) >> 15;
                gi = (gi * contrastFactorIndex) >> 15;
                bi = (bi * contrastFactorIndex) >> 15;

                // Transform back to range [0, 255]
                ri = ri + 128;
                gi = gi + 128;
                bi = bi + 128;
                // Clamp to byte boundaries
                red = (byte)(ri > 255 ? 255 : (ri < 0 ? 0 : ri));
                green = (byte)(gi > 255 ? 255 : (gi < 0 ? 0 : gi));
                blue = (byte)(bi > 255 ? 255 : (bi < 0 ? 0 : bi));
                result.SetValue[index] = (alpha << 24) | (red << 16) | (green << 8) | blue;
            }
        }

//additional Buffer.BlockCopy(tempPixels, 0, inputPixels, 0, tempPixels.Length);

        return result;
    }

The 'SetValue' was 'pixels' in the original sample but Pixels does not exist in this object on WP8.1.

What is the equivalent please?

The following imaging sdk has the filtering that your are trying to use plus much much more http://developer.nokia.com/lumia/nokia-apis/imaging — Stuart Smith, Dec 19 '14 at 21:37

score 1 · Accepted Answer · edited May 23 '17 at 11:44

1

You want to modify the int[] tempPixels array. Once you are finished with that you want to copy the tempPixel array back to the result.PixelBuffer. You can use Buffer.BlockCopy to copy a block to another block.

Full example: how to adjust brightness: Adjust Brightness WriteableBitmap 8.1

Full example: grayscale an image: Grayscale an Image WriteableBitmap 8.0

Remember to add in System.IO and System.Runtime.InteropServices.WindowsRuntime for the solutions above to work.

I also included the full 8.1 project here on my OneDrive: Adjust Brightness Project 8.1

edited May 23 '17 at 11:44

Community

1
1

answered Dec 20 '14 at 04:24

Chubosaurus Software

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Hi, still getting errors like: 'Windows.Storage.Streams.IBuffer' does not contain a definition for 'AsStream' cannot convert from 'Windows.Storage.Streams.IBuffer' to 'Windows.Storage.Streams.IRandomAccessStream' cannot convert from 'Windows.Storage.Streams.IBuffer' to 'System.Array' – Andrew Simpson Dec 20 '14 at 10:50
I believe this is because I am create a Windows Phone Store App – Andrew Simpson Dec 20 '14 at 10:50
@AndrewSimpson are you running 8.1 Silverlight or 8.1 runtime? – Chubosaurus Software Dec 21 '14 at 05:25
8.1 runtime. I am new to wp development. Had not realised there were 2 types – Andrew Simpson Dec 21 '14 at 08:34
@AndrewSimpson `using (Stream input = writeable_bitmap.PixelBuffer.AsStream())` should work in 8.1 runtime. Did you forget to include System.IO? – Chubosaurus Software Dec 22 '14 at 05:21
Hi, thanks for commenting. Yes, I have included that namespace :). The error is telling me that Windows.Storage.Streams.IBuffer does not contain a definition for AsStream – Andrew Simpson Dec 22 '14 at 14:58
@AndrewSimpson must being missing some includes. `using System.Runtime.InteropServices.WindowsRuntime;` perhaps? – Chubosaurus Software Dec 22 '14 at 21:44
1

@AndrewSimpson checked out the onedrive project: https://skydrive.live.com/redir?resid=9F2F16D176D29EFC!17211 (it should almost convert to phone 8.1 runtime 1:1) – Chubosaurus Software Dec 22 '14 at 21:55
thanks for all that. Just ported it all over and it works. I was missing the using System.Runtime.InteropServices.WindowsRuntime; namespace - lol – Andrew Simpson Dec 23 '14 at 17:15
@AndrewSimpson Wweet, glad it worked out for you. I updated the solution to added in the new info. – Chubosaurus Software Dec 23 '14 at 23:59
@ChubosaurusSoftware How to change each image pixel color of downloaded png image and store it in isolated storage after color has been changed? – Kinjan Bhavsar Jan 12 '16 at 07:22

Adjust image in Windows Phone 8.1

1 Answers1