CODEWITHSUNDEEP
c#wpf
Tokfrans
Tokfrans

Reputation: 1959

Set bits per pixel in WPF-Desktop program

I noticed ugly banding issues when using Gradients in WPF, and saw that a solution was to set the "bits per pixel" property to 32. The thing is that the property seem to be Windows Phone only, ie not working on a program for desktop devices, since trying to add this string in the ApplicationManifest didn't seem to do anything.

Does anyone know if/how I can set this property?

Thank you.

My function which draws the gradients:

public LinearGradientBrush getGradient(Color c1, Color c2, double opacity)
{
    LinearGradientBrush gradient = new LinearGradientBrush();
    gradient.StartPoint = new Point(0, 0);
    gradient.EndPoint = new Point(1, 1);
    gradient.GradientStops.Add(new GradientStop(c1, 0.0));
    gradient.GradientStops.Add(new GradientStop(c2, 1.0));
    gradient.Opacity = opacity;
    return gradient;
}

I draw the gradients off of the two most dominant colors in an AlbumCover. You can see the two colors on the top left of the window. I then call the getGradient-function with this:

getGradient(Colors[0], Colors[1], 0.5); // 0.5 is dynamic depending on the brightness of those colors. Tried with 1 opacity but it's still the same.

Here are the sample images (in PNG and uploaded without compression)

As you can see, there is banding going on. There are worse examples but I can't remember what Cover gave it.

Please notice that Image1 does not have banding on it's AlbumCover. Even though there is a gradient on it.

Upvotes: 1

Views: 525

Answers (2)

Tokfrans
Tokfrans

Reputation: 1959

After digging around a long time I finally found the best solution:

Adding a little bit of noise to the image! This does mean I have to draw the gradient myself, but I believe the quality will be much better.

I will update this post with the algorithm itself and examples when I'm done writing.

Stay tuned I guess.

Upvotes: 1

Lukasz M
Lukasz M

Reputation: 5723

By doing a quick search I found some suggestions that the issue may be just a visual effect that is a result of having only 256 values for each of R, G and B channels that defines a color and the way that gradients work. If You try to cover a large area with a gradient, it'll divide it into smaller areas filled with solid colors, slightly changing between neighbouring areas. Additionally, there is an optical illusion called Mach bands that makes the borders of the areas even more visible.

Take a look at those links for more information and some suggested solutions:

Upvotes: 2

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