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#1 Posted : Sunday, November 19, 2017 1:32:09 PM(UTC)

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I am trying to apply a tint to a bitmap that has been processed through the GreenRemoval object but am being unsuccessful at it and was wondering if anyone could help me with it.

What I have so far is that I pass in a cv image into my method and then create a bitmap object from that. This image is the one with the green screen background. I then process that image via the GreenRemoval object. Next I try to apply a tint to the image and finally I draw that image onto a background image. If I do not apply the tint the image turns out perfect with the GreenRemoval process but when I try to apply the tint I only get the original image with the green removed with the tint applied but the background image is not present. I think what is happening is that I am losing the transparency when I apply the tint. Is there a way to apply the tint and keep the transparency so that when I draw that on top of the background image the background image is as intended and only the processed image has a tint on it?

I have posted the code that I have so far:


private void ProcessGreenScreen(string filename, cv.Image<Bgr, byte> img)
        // Do we have a valid green screen background?
        if (Globals.AppliedBackground != null)
            // If so get a bitmap object from the cv image.
            using (Aurigma.GraphicsMill.Bitmap bmp = new Aurigma.GraphicsMill.Bitmap(img.Bitmap))
                // Create a new greenscreen removal object.
                using (var GreenRemove = new GreenScreenRemoval())
                    // Remove the green background from the image.
                    Aurigma.GraphicsMill.Bitmap bitmapNoGreen = GreenRemove.Apply((bmp));

                    // Do we need to apply a tint to the image?
                    if (Globals.FiltersEnabled && Globals.AppliedFilter != null && Globals.AppliedFilter.NoFilter == false)
                        // If so, send it to the method that applies the tint.
                        _cameraBase.TintedFilter(new RgbColor(Globals.AppliedFilter.Red, Globals.AppliedFilter.Green, Globals.AppliedFilter.Blue), ref bitmapNoGreen);

                    // Get the green screen background image filename.
                    string backgroundImage = Globals.GreenscreenFolder + "\\" + Globals.AppliedBackground.Filename;

                    // Create a bitmap object from the file.
                    using (var bckgrnd = new Aurigma.GraphicsMill.Bitmap(backgroundImage))
                        // Does the green screen background image need to be resized?
                        if (Globals.AppliedBackground.IsValidDimensions == false)
                            // If so, resize it now.
                            bckgrnd.Transforms.Resize(new Size((int)Globals.CameraDefaultWidth, (int)Globals.CameraDefaultHeight), ResizeInterpolationMode.Lanczos3, ResizeMode.ImageFill);

                        // Draw the image onto the background image.
                        bckgrnd.Draw(bitmapNoGreen, 0, 0, CombineMode.Alpha);

                        // Change the DPI of the image.
                        bckgrnd.DpiX = Globals.PrintDPI;
                        bckgrnd.DpiY = Globals.PrintDPI;

                        // Save the image as a jpg
                        var jpegSettings = new Aurigma.GraphicsMill.Codecs.JpegSettings();
                        jpegSettings.Quality = 90;
                        jpegSettings.UseSubsampling = false;
                        jpegSettings.IsProgressive = true;

                        bckgrnd.Save(filename, jpegSettings);
            log.Debug("Green Screen Background not loaded");
    catch (Exception e)

And the code that actually applies the tint is as follows:


public void TintedFilter(RgbColor color, ref Aurigma.GraphicsMill.Bitmap bmp)
    if (bmp.ColorProfile == null)
        bmp.ColorProfile = ColorProfile.FromSrgb();    

    var labColor = RgbToLabColor(color);
    var a = labColor.A;
    var b = labColor.B;

    using (var lChannel = new Aurigma.GraphicsMill.Bitmap())
        // Convert to Lab color space and get lightness channel
        using (var labConverter = new Aurigma.GraphicsMill.Transforms.ColorConverter(Aurigma.GraphicsMill.PixelFormat.Format24bppLab))
        using (var splitter = new LabChannelSplitter())
            splitter.L = lChannel;

            Pipeline.Run(bmp + labConverter + splitter);

        // Create a and b channels, combine with lightness channel and convert to RGB color space
        using (var combiner = new LabChannelCombiner())
        using (var aChannel = new Aurigma.GraphicsMill.Bitmap(lChannel.Width, lChannel.Height, Aurigma.GraphicsMill.PixelFormat.Format8bppGrayscale, new GrayscaleColor((byte)(a + 127))))
        using (var bChannel = new Aurigma.GraphicsMill.Bitmap(lChannel.Width, lChannel.Height, Aurigma.GraphicsMill.PixelFormat.Format8bppGrayscale, new GrayscaleColor((byte)(b + 127))))
        using (var rgbConverter = new Aurigma.GraphicsMill.Transforms.ColorConverter(Aurigma.GraphicsMill.PixelFormat.Format24bppRgb))
            combiner.L = lChannel;
            combiner.A = aChannel;
            combiner.B = bChannel;

            rgbConverter.DestinationProfile = ColorProfile.FromSrgb();

            Pipeline.Run(combiner + rgbConverter + bmp);

Andrey Semenov  
#2 Posted : Tuesday, November 21, 2017 3:20:23 AM(UTC)
Andrey Semenov

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Hi Lauren,

Just save original alpha channel in the beginning of TintedFilter() function and then add it to the bitmap after applying the tint:

public static void TintedFilter(RgbColor color, ref Aurigma.GraphicsMill.Bitmap bmp)
    var transparencyChannel = bmp.Channels[Channel.Alpha];

    // ... Existing code ...

    using (var combiner = new RgbChannelCombiner())
        combiner.R = bmp.Channels[Channel.Red];
        combiner.G = bmp.Channels[Channel.Green];
        combiner.B = bmp.Channels[Channel.Blue];
        combiner.A = transparencyChannel;

        Pipeline.Run(combiner + bmp);


Edited by user Tuesday, November 21, 2017 3:23:13 AM(UTC)  | Reason: Not specified

thanks 1 user thanked Andrey Semenov for this useful post.
lauren@photoboothsupplyco.com on 11/21/2017(UTC)
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