Hello,

I am programming an image application with a GUI.
I open a grayscale image like this:

String^ s = openFileDialog1->FileName;
s = s->Substring(s->LastIndexOf('\\') + 1, (s->Length - s->LastIndexOf('\\')) - 1);
InputImageFileName = s;
bmpInputImage = gcnew System::Drawing::Bitmap(openFileDialog1->FileName);

then I create a new image

binaryImage=gcnew System::Drawing::Bitmap(bmpInputImage);

and I want to work with this image as a unsigned char* so I can use each value of the image to make an histogram and more operations.

I have found that but in the case that it works,(I am not sure), I do not know how to use it:

System::Drawing::Image::Save(System::String^ filename, System::Drawing::Imaging::ImageFormat^  format)
//then I will apply format->ToString();

Could anyone of you help me?
Thanks in advanced!!

You can't just cast an image into a char array. Besides: Microsoft has given us a lot of functions to play with:

Bitmap^ binaryImage=gcnew System::Drawing::Bitmap(bmpInputImage);
Color pixelColor = binaryImage->GetPixel( 1, 1 ); //get pixel x=1 y=1
Byte g = pixelColor.G;
Byte b = pixelColor.B;
Byte r = pixelColor.R;
Byte a = pixelColor.A;

Now the vars r,g,b,a will hold the color values of pixel 1,1
(NOTE: this is untested)

so this way I have got the colour value but how can I change the bytes to unsigned char?
because the idea is to have the value of the pixels of a bitmap image so that I can make an histogram and to access to this bitmap like this:

int histoArray[256];
for(unsigned int a=0;a<256;a++)
{
       for(unsigned int b=0;b<256;b++)
{
		histoArray[bitmap[a][b]]+=1;
}
}

Tell me if this works:

unsigned char valr = (unsigned char)pixelColor.G;
std::cout << valr << '\n';

if not: please post the error message. I haven't worked with these kinds of thing for a while..

It does not work. Look the value of valG. I think that the casting is not working properly.

The value is 2. What value are you expecting for green? In other words, what color is the pixel?

the color is what I was expecting but I don't understand what is the meaning of the symbol next to the value. Depending on the pixel there is a symbol or a number. What does it mean?

because it's a char your debugger will show you the character that the ASCII value represents. But since decimal 2 = 'start of text character' the debugger shows a little square :) If the value was 33 it would have shown you a '!'.

Don't worry about it, you can still make calculations with the value

Here's the ASCII table

ok!!ASCII...Good to know!!
thank you so much for your help, I am going to mark this thread as solved.
Thank you!!