saving an image using 'imwrite'

I'm trying to save an grayscale image to a file using

imagesc(Nv)
imwrite(Nv,'C:\Users\bostock_h\Documents\Images\chargemap.jpg')

but for some reason this just creates a file which is just white with the wrong dimensions. But I know 'Nv' is fine because the 'imagesc' brings up the image in MATLAB and it is correct.

Answer 1

[Walter Roberson]

imagesc() automatically scales data so that the minimum value maps to the first color and the maximum value maps to the last color. If your data does not happen to be in the range 0 to 1 for floating point values, or 0 to 255 for uint8, or 0 to 65535 for uint16, then the image that imwrite() creates is not going to be the image you want.