通过像素BMP C＃的例外情况

Question

Im using the following code to travel though the pixels of a BMP as this

for (int i = 0; i <= Image.Width; i++)
 {
    for (int j = 0; j <= Image.Height; j++)
    {
              color = Image.GetPixel(i, j); //get 
    }

 }

but im getting a exception

System.ArgumentOutOfRangeException was unhandled
  Message="Parameter must be positive and < Height.\r\nParameter name: y"
  Source="System.Drawing"
  ParamName="y"

I have no clue why im getting this.. im using a BMP with valid heights and same code with hard-coded values working correctly

@Odded

No:1 Shows what i needed and no 2 is whats happening with ur code any idea?

Answer 1

You have an off-by-one error in your loops.

If the image Height and Width is 100, to get the "last" pixel you will need to call it as GetPixel(99,99) .

for (int i = 0; i < Image.Width; i++)
 {
    for (int j = 0; j < Image.Height; j++)
    {
              color = Image.GetPixel(i, j); //get 
    }

 }

Answer 2

Just change Height and Width. This is such an example of looking too far in your own code - this brings back so many memories..

for(int i=0;i<BMP.Height;i++)
{
   for(int j=0;j<BMP.Width;j++)
   {
      color = BMP.GetPixel(j,i);    
   }
}

Answer 3

Swap the two loops.

for(int j=0; j<BMP.Height; j++)
{
   for(int i=0; i<BMP.Width; i++)
   {
      color = BMP.GetPixel(i,j);     
   }
}

Everyone is focusing on width and height, that's NOT the solution. GetPixel takes two arguments, x and y . The y coordinate must be the outer loop to get the order you want.

The x-coordinate always runs from 0 ... Width-1

Answer 4

Flip your loops around. The outer loop should be the height and the inner loop should be the width if you want it to behave like the 1st image.

Answer 5

Just swap around the Width and Height:

for(int i=0;i<BMP.Height;i++){

   for(int j=0;j<BMP.Width;j++){
      color=BMP.GetPixel(j, i);
   }
}

I've also swapped around i and j so that GetPixel works correctly

Answer 6

Let's make this simple and use x and y instead of i and j so it's easier to think about in Cartesian coordinates.

//For each height, loop through all pixels at that height.
for(int y=0; y < BMP.Height; y++)
{
    for(int x=0; x < BMP.Width; x++)
    {
        color = BMP.GetPixel(x,y);     
    }
}