I can't pass parameter to method.

Tyler Miles

Hi, i am new with C# and OOP.

I created a method (it blurs an image) . And it works well. I will create another method. And i need blurred image as input parameter. But i don't know how to do this? (I tried something. But none of them didn't work)

Here is my try:

private void sliderKernel_MouseUp(object sender, MouseEventArgs e)
{
Filtreler f1 = new Filtreler(); //Filtreler is name of my class
f1.Img = new Bitmap(pBox_SOURCE.Image);
int kernelsize = sliderKernel.Value;
Bitmap MeanImg = f1.meanfilter(kernelsize, f1.Img); //this method works well.now, i would like to use MeanImg
pBox_PROCESSED.Image = MeanImg;
f1.CorrectShade(f1.Img, MeanImg); //But i can't. All the pixel values are come as zero
pBoxShadeCorrection.Image = MeanImg;
}

public Bitmap Img { get; set; } //my Properties
public Color PixelValue { get; set; }

public Bitmap meanfilter(int kernelsize, Bitmap InputImage)
{
Bitmap CikisResmi = new Bitmap(GirisResmi.Width, GirisResmi.Height);
//blurring operations
return CikisResmi;
//I blurred the image. No problem with this method
}

public Bitmap CorrectShade(Bitmap InputImage,Bitmap BlurredImage)
{
Color PixelVauleBlurred;
int divR,x,y;
int ImgWidth = InputImage.Width;
int ImgHeight = InputImage.Height;
for (x = 0; x < ImgWidth; x++)
{
for (y = 0; y < ImgHeight; y++)
{
PixelVauleBlurred = BlurredImage.GetPixel(x, y);
PixelValue = InputImage.GetPixel(x, y);
divR = Convert.ToInt16(1f*OkunanRenk.R / PixelVauleBlurred.R); //Error line //Error message:System.DivideByZeroException: 'Attempted to divide by zero.'
BlurredImage.SetPixel(x, y, Color.FromArgb(divR, divR, divR));
}
}
return BlurredImage;
}

7 Replies

Know the answer? Post it — somebody with the same question will find it here.

Tyler Miles7y ago
I changed my methods and now it works. But i can't edit question.
I didn't change this part, but it works properly. Are there any problem with this usage?
Filtreler f1 = new Filtreler(); //Filtreler is name of my class
f1.Img = new Bitmap(pBox_SOURCE.Image);
int kernelsize = sliderKernel.Value;/Bitmap MeanImg = f1.meanfilter(kernelsize, f1.Img);
pBox_PROCESSED.Image = MeanImg;
Bitmap deneme = f1.CorrectShade(f1.Img, MeanImg);
pBoxShadeCorrection.Image = deneme;
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Mario Scheeren7y ago
You cannot pass a Property of an instance ... but:

f1.CorrectShade((Bitmap)f1.Img.Clone(), MeanImg);

or

var tmp = f1.Img;
f1.CorrectShade(tmp, MeanImg);

would work. The "problem" is, that a property is part of an instance and you only have a pointer to that instance. So to pass this value you will have to kind of create a pointer to it.
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Afzaal Ahmad Zeeshan7y ago
If your red parameter is always zero, that means you need to check alternative ways to perform the blurring. Did you try reading some commonly used algorithms to study if they follow the same approach?
0
Tyler Miles7y ago
You are right. I changed that part. But i can't edit post.

But that is not my main problem. My main problem is PixelVauleBlurred.R
is always equal to zero (all pixel values). And when i check MeanImg from pBox_PROCESSED.Image i see that there is no problem there. But when i try yo use MeanImg as a input it comes as a blank image. (All pixel values are 0) How can i use MeanImg as a input properly?
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Afzaal Ahmad Zeeshan7y ago
For one thing, this is not a compilation error and would exist on runtime only and for the second, the error message clearly tells what is going wrong here,
Error message:System.DivideByZeroException: 'Attempted to divide by zero.'
This means that the terms you are using to divide a number with is zero; which is a basic mathematics error and you cannot do that; see here, https://en.wikipedia.org/wiki/Division_by_zero
How you can solve this? You cannot. However, you can still try to prevent the error from showing up, and to do that just do this,
// Instead of this
divR = Convert.ToInt16(1f*OkunanRenk.R / PixelVauleBlurred.R);

// Do this
if(PixelVauleBlurred.R > 0) {
    divR = Convert.ToInt16(1f * OkunanRenk.R / PixelVauleBlurred.R);
}
This will safely divide the value and save it in divR, otherwise divR will be zero by default. You must always take precausions in your code, to prevent runtime exceptions from happening every now and then.
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Tyler Miles7y ago
I will change that part. But that's not my only problem. All of the pixels comes out as zeros from parameter. (my meanfilter works properly and MeanImg is like i desired)
https://ibb.co/ZVThX09
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Mario Scheeren7y ago
Well actually your method is using really slow method calls GetPixel / SetPixel.

Check out this: https://softwarebydefault.com/2013/06/09/image-blur-filters/

or this: https://docs.microsoft.com/en-us/dotnet/api/system.drawing.bitmap.lockbits

to gain performance.

The problem within your method is that value of PixelVauleBlurred.R can be 0!

divR = Convert.ToInt16(1f*OkunanRenk.R / Math.Max(1, PixelVauleBlurred.R));

If you just want the image to be not really to be recognized, then
create a new bitmap, draw the content of the first on it and above that a semi transparent rectangle filled with argb 20, 255, 255, 255.
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