Grayscale image: Difference between revisions

 

=={{header|Ada}}==

type Grayscale_Image is array (Positive range <>, Positive range <>) of Luminance;

Conversion to a grayscale image:

function Grayscale (Picture : Image) return Grayscale_Image is

type Extended_Luminance is range 0..10_000_000;

return Result;

end Grayscale;

Conversion to a color image:

function Color (Picture : Grayscale_Image) return Image is

Result : Image (Picture'Range (1), Picture'Range (2));

return Result;

end Color;

 

=={{header|C}}==

Definition for a grayscale image.

 

typedef unsigned char luminance;

typedef luminance pixel1[1];

} grayimage_t;

typedef grayimage_t *grayimage;

 

The same as <tt>alloc_img</tt>, but for grayscale images.

 

grayimage alloc_grayimg(unsigned int width, unsigned int height)

{

return img;

}

 

Convert from ''color'' image to ''grayscale'' image.

 

grayimage tograyscale(image img)

{

return timg;

}

 

And back from a ''grayscale'' image to a ''color'' image.

 

{

unsigned int x, y;

return timg;

}

 

'''Notes'''

* <tt>tocolor</tt> and <tt>tograyscale</tt> do not free the previous image, so it must be freed normally calling <tt>free_img</tt>. With a cast we can use the same function also for grayscale images, or we can define something like

 

#define free_grayimg(IMG) free_img((image)(IMG))

 

* ''Luminance'' is rounded. Since the C implementation is based on unsigned char (256 possible values per components), L can be at most 255.0 and rounding gives 255, as we expect. Changing the color_component type would only change 256, 255.0 and 255 values here written in something else, the code would work the same.

 

Conversion to a grayscale image:

let to_grayscale ~img:(_, r_channel, g_channel, b_channel) =

let width = Bigarray.Array2.dim1 r_channel

done;

(gray_channel)

 

Conversion to a color image:

let to_color ~img:gray_channel =

let width = Bigarray.Array2.dim1 gray_channel

g_channel,

b_channel)

 

=={{header|Vedit macro language}}==