staying within boundaries of image?

Programmer Question

So I am to loop through copyFrom.pixelData and copy it into pixelData.

I realize that I need to check the conditions of i and j, and have them not copy past the boundaries of pixelData[x][y],

I need another 2 loops for that? I tried this, but was getting segmentation fault..
Is this the right approach?

void Image::insert(int xoff, int yoff, const Image& copyFrom, Color notCopy)
{
    for (int x = xoff; x < xoff+copyFrom.width; x++) {
            for (int y = yoff; y < yoff+copyFrom.height; y++) {
        for (int i = 0; i<width; i++){
            for (int j = 0; j<height; j++){
        if (copyFrom.pixelData[i][j].colorDistance(notCopy)>20 )
            pixelData[x][y]=copyFrom.pixelData[i][j];
            }
        }
        }
    }
}

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