reading image data

[Maejie]

I read an image into a byte array this way

for i=0 to WIDTH
  for j=0 to HEIGHT
     data[i,j]=(byte)img.GetPixel(i,j).ToArgb(); 

but when I show it, the image becomes gray . I am so confused.

Could someone help me please ? Thank you.

[BigEd781]

Wrell, ToArgb doesn't return a byte, it returns an int, so you are overflowing. If you want a byte array you can do this:

MemoryStream ms = new MemoryStream();
bmp.Save (ms, someFormat);
	
byte[] bmpBytes = ms.GetBuffer();
bmp.Dispose();
ms.Close();

Also, if your images are even moderately sized, looping through each pixel using GetPixel and SetPixel is going to be really slow.

[Maejie]

Thank you BigEd781,
I do as what you suggest me,
I now don't know how to change the byte array back into an image ?

I have tried

Image img=Image.FromStream(ms);

but the compiler states that ms is an invalid argument in the debug view, although I find that all of its properties are initialised.

[Arjay]

Thank you BigEd781,
I do as what you suggest me,
I now don't know how to change the byte array back into an image ?

I have tried

Image img=Image.FromStream(ms);

but the compiler states that ms is an invalid argument in the debug view, although I find that all of its properties are initialised.

Did you call ms.Close(); as Big Ed suggested?

Once you call close on the memory stream you can't use it anymore.

[Maejie]

Thank you for your reply,
I do it like this

byte[] UseStreamToByte(Image img)
{
    MemoryStream ms=new MemoryStream();
    img.Save(ms, ImageFormat.Png);
    byte [] temp=ms.GetBuffer();
    ms.Closer();
    return temp;
}
///do some processing
Image UseStreamToImg(byte[] imgDt)
{
   MemoryStream ms=new Memorystream(imgDt);
   Image img=ms.FromStream(ms);  // this is where I get the error "invalid parameter/argument ms"
   ms.Close();
   return img;
} 

[Arjay]

Image UseStreamToImg(byte[] imgDt)
{
   MemoryStream ms=new Memorystream(imgDt);
   Image img=ms.FromStream(ms);  // this is where I get the error "invalid parameter/argument ms"
   ms.Close();
   return img;
}

Should the red highlighted portion be Image instead of ms?

[Maejie]

Thank you, yes it was my typo, it should have been |Image.FromStream(ms)| but still I have that exception irresolvable.