C / C++ / MFC

Spartan16 wrote:

How would i do that...

Spartan16 wrote:

...in cmd what do i type to run the program...

// ratio of input size to output size
factor1 = inputPoints / outputPoints

// loop over output
for (current=0 to outputPoints-1)
{
  // center of our input pixel is here. it's probably fractional.
  inputPixelLocation = current * factor1

  // get the two pixels on either side of that center point
  input1 = pixel[floor(inputPixelLocation)]
  input2 = pixel[floor(inputPixelLocation) + 1]

  // the fractional part of this tells us how close we are to the left-most source pixel.
  factor2 = fractional_part_of(inputPixelLocation) 

  // average of the two pixels, weighted by factor2
  output = input1 * factor2 + input2 * (1.0 - factor2)
}

factor1X = inputPointsX / outputPointsX
factor1Y = inputPointsY / outputPointsY

// vertical loop
for (currentY=0 to outputPointsY-1)
{
  // find the vertical factor
  inputPixelLocationY = currentY * factor1Y

  // horizontal loop
  for (currentX=0 to outputPointsX-1)
  {
    // find horizontal factor
    inputPixelLocationX = currentX * factor1X

    floorX = floor(inputPixelLocationX)
    floorY = floor(inputPixelLocationY)

    // get four pixels: X,Y - X+1,Y - X,Y+1, X+1,Y+1
    input1 = pixel[floorX ][floorY]
    input2 = pixel[floorX + 1][floorY]
    input3 = pixel[floorX][floorY + 1]
    input4 = pixel[floorX + 1][floorY + 1]

    // two factors
    factor2X = fractional_part_of(inputPixelLocationX) 
    factor2Y = fractional_part_of(inputPixelLocationY) 

    factor2X_inverse = 1.0 - factor2X 
    factor2Y_inverse = 1.0 - factor2Y 

    // average of the four pixels, weighted by the 2 factor2's
    outval = input1 * factor2X * factor2Y + 
             input2 * factor2X_inverse * factor2Y + 
             input3 * factor2X * factor2Y_inverse + 
             input4 * factor2X_inverse * factor2Y_inverse

    output[currentX][currentY] = outval
  }
}