How to save Bitmap with background in C#?

Question

I'm using Windows.UI is Winform in C#. I have file images in Photoshop; it was transparent. Like this:

So, I want the background to this picture; it will show. Example, I pick an orange colour.

I tried with:

gbmp.Clear(Color.Orange);

But it overrides my picture; the picture only has one colour is an orange.

My code to do this:

Graphics gra = Graphics.FromImage(img);

Bitmap bmp = new Bitmap(@"" + pathToFile);
panel2.BackgroundImage = bmp;
Graphics gbmp = Graphics.FromImage(bmp);
gbmp.Clear(Color.Orange);

gbmp.DrawImage(
DrawText("WHAT UP?", fontType, myColorLabel1,
    Color.Transparent),
Point.Round(StretchImageSize(new Point(activeLabels[1].Location.X, activeLabels[1].Location.Y), panel2)));
gra.Dispose();
Guid id = Guid.NewGuid();
ScaleImage(bmp, witdhImg, heightImg)
    .Save(linkLocation + "\\" + id + "." + imgType,
        ImageFormat.Png);

I find this article like How to Change Pixel Color of an Image in C#.NET

Here is the Solution I have done with Pixels.

Attaching the source code so one can try the exact and get the result.

I have sample images of 128x128 (Width x Height).

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.IO;
//using System.Globalization;

namespace colorchange
{
   class Program
   {
      static void Main(string[] args)
      {
          try
          {
              Bitmap bmp = null;
              //The Source Directory in debug\bin\Big\
              string[] files = Directory.GetFiles("Big\\");
              foreach (string filename in files)
              {
                 bmp = (Bitmap)Image.FromFile(filename);                    
                 bmp = ChangeColor(bmp);
                 string[] spliter = filename.Split('\\');
                 //Destination Directory debug\bin\BigGreen\
                 bmp.Save("BigGreen\\" + spliter[1]);
              }                                                 
           }
           catch (System.Exception ex)
           {
              Console.WriteLine(ex.ToString());
           }            
       }        
       public static Bitmap ChangeColor(Bitmap scrBitmap)
       {
          //You can change your new color here. Red,Green,LawnGreen any..
          Color newColor = Color.Red;
          Color actualColor;            
          //make an empty bitmap the same size as scrBitmap
          Bitmap newBitmap = new Bitmap(scrBitmap.Width, scrBitmap.Height);
          for (int i = 0; i < scrBitmap.Width; i++)
          {
             for (int j = 0; j < scrBitmap.Height; j++)
             {
                //get the pixel from the scrBitmap image
                actualColor = scrBitmap.GetPixel(i, j);
                // > 150 because.. Images edges can be of low pixel colr. if we set all pixel color to new then there will be no smoothness left.
                if (actualColor.A > 150)
                    newBitmap.SetPixel(i, j, newColor);
                else
                    newBitmap.SetPixel(i, j, actualColor);
             }
          }            
          return newBitmap;
       }
   }
}

//Below is the sample image and different results by applying different colour

Code modifications will be highly appreciated.

It changes object in the image; it can't change the background.

Have you any idea to change this code?

Answer 1

you are using this line :

gbmp.Clear(Color.Orange);

after load your img

using draw image maybe help you

first make a bitmap of size your img

Bitmap bmp = new Bitmap(width, height)

clear it as your colour :

bmp.Clear(Color.Orange);

then draw the img on bmp

also look this links, maybe help u :

Using Graphics.DrawImage() to Draw Image with Transparency/Alpha Channel

https://msdn.microsoft.com/en-us/library/8517ckds%28v=vs.110%29.aspx