From a2fb7bf3228df080fd277ba18f4996fc518b7835 Mon Sep 17 00:00:00 2001
From: RKrom <robin@getgreenshot.org>
Date: Thu, 7 Feb 2013 13:19:01 +0000
Subject: [PATCH] Added "Adjust" to the ImageHelper, this can change the
 brightness, contrast and gamma.

git-svn-id: http://svn.code.sf.net/p/greenshot/code/trunk@2469 7dccd23d-a4a3-4e1f-8c07-b4c1b4018ab4
---
 GreenshotPlugin/Core/Effects.cs     | 27 ++++++++++++++++++++++
 GreenshotPlugin/Core/ImageHelper.cs | 36 +++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/GreenshotPlugin/Core/Effects.cs b/GreenshotPlugin/Core/Effects.cs
index dcbaf9ff0..9f0224b03 100644
--- a/GreenshotPlugin/Core/Effects.cs
+++ b/GreenshotPlugin/Core/Effects.cs
@@ -111,6 +111,33 @@ namespace Greenshot.Core {
 		}
 	}
 
+	/// <summary>
+	/// AdjustEffect
+	/// </summary>
+	public class AdjustEffect : IEffect {
+		public AdjustEffect() : base() {
+			Contrast = 1f;
+			Brightness = 1f;
+			Gamma = 1f;
+		}
+		public float Contrast {
+			get;
+			set;
+		}
+		public float Brightness {
+			get;
+			set;
+		}
+		public float Gamma {
+			get;
+			set;
+		}
+		public Image Apply(Image sourceImage, out Point offsetChange) {
+			offsetChange = Point.Empty;
+			return ImageHelper.Adjust(sourceImage, Brightness, Contrast, Gamma);
+		}
+	}
+
 	/// <summary>
 	/// InvertEffect
 	/// </summary>
diff --git a/GreenshotPlugin/Core/ImageHelper.cs b/GreenshotPlugin/Core/ImageHelper.cs
index 0ac5739c5..033517b8f 100644
--- a/GreenshotPlugin/Core/ImageHelper.cs
+++ b/GreenshotPlugin/Core/ImageHelper.cs
@@ -1029,6 +1029,42 @@ namespace GreenshotPlugin.Core {
 			return newImage;
 		}
 
+		/// <summary>
+		/// Adjust the brightness, contract or gamma of an image.
+		/// Use the value "1.0f" for no changes.
+		/// </summary>
+		/// <param name="sourceImage">Original bitmap</param>
+		/// <returns>Bitmap with grayscale</returns>
+		public static Image Adjust(Image sourceImage, float brightness, float contrast, float gamma) {
+			//create a blank bitmap the same size as original
+			// If using 8bpp than the following exception comes: A Graphics object cannot be created from an image that has an indexed pixel format. 
+			Bitmap newBitmap = CreateEmpty(sourceImage.Width, sourceImage.Height, PixelFormat.Format24bppRgb, Color.Empty, sourceImage.HorizontalResolution, sourceImage.VerticalResolution);
+			float adjustedBrightness = brightness - 1.0f;
+			// get a graphics object from the new image
+			using (Graphics graphics = Graphics.FromImage(newBitmap)) {
+				// create the grayscale ColorMatrix
+				ColorMatrix colorMatrix = new ColorMatrix(
+					new float[][] {
+						new float[] {contrast, 0, 0, 0, 0}, // scale red
+						new float[] {0, contrast, 0, 0, 0}, // scale green
+						new float[] {0, 0, contrast, 0, 0}, // scale blue
+						new float[] {0, 0, 0, 1.0f, 0}, // don't scale alpha
+						new float[] {adjustedBrightness, adjustedBrightness, adjustedBrightness, 0, 1}
+					});
+
+				//create some image attributes
+				ImageAttributes attributes = new ImageAttributes();
+
+				//set the color matrix attribute
+				attributes.SetColorMatrix(colorMatrix);
+
+				//draw the original image on the new image using the grayscale color matrix
+				graphics.DrawImage(sourceImage, new Rectangle(0, 0, sourceImage.Width, sourceImage.Height), 0, 0, sourceImage.Width, sourceImage.Height, GraphicsUnit.Pixel, attributes);
+			}
+
+			return newBitmap;
+		}
+
 		/// <summary>
 		/// Create a new bitmap where the sourceBitmap is in grayscale
 		/// </summary>