im = imread('oranges1.pgm');
class(im)

ans =

uint8

im = double(im);
figure
image(im)
imagesc(im)
colormap(gray)
help colormap

 COLORMAP Color look-up table.
    COLORMAP(MAP) sets the current figure's colormap to MAP.
    COLORMAP('default') sets the current figure's colormap to
    the root's default, whose setting is JET.
    MAP = COLORMAP retrieves the current colormap. The values
    are in the range from 0 to 1.
    COLORMAP(AX,...) uses the figure corresponding to axes AX
    instead of the current figure.
 
    A color map matrix may have any number of rows, but it must have
    exactly 3 columns.  Each row is interpreted as a color, with the
    first element specifying the intensity of red light, the second 
    green, and the third blue.  Color intensity can be specified on the
    interval 0.0 to 1.0.
    For example, [0 0 0] is black, [1 1 1] is white, 
    [1 0 0] is pure red, [.5 .5 .5] is gray, and
    [127/255 1 212/255] is aquamarine.
    
    Graphics objects that use pseudocolor  -- SURFACE and PATCH objects,
    which are created by the functions MESH, SURF, and PCOLOR -- map
    a color matrix, C, whose values are in the range [Cmin, Cmax],
    to an array of indices, k, in the range [1, m].
    The values of Cmin and Cmax are either min(min(C)) and max(max(C)),
    or are specified by CAXIS.  The mapping is linear, with Cmin
    mapping to index 1 and Cmax mapping to index m.  The indices are
    then used with the colormap to determine the color associated
    with each matrix element.  See CAXIS for details.
  
    Type HELP GRAPH3D to see a number of useful colormaps.
 
    COLORMAP is an M-file that sets the Colormap property of a figure.
 
    See also HSV, CAXIS, SPINMAP, BRIGHTEN, RGBPLOT, FIGURE, COLORMAPEDITOR.

h = hist(im, 256);
figure
plot(h)
h2 = conv(h,ones(1,10));
??? Error using ==> conv
A and B must be vectors.

size(h)

ans =

   256   400

h = hist(im(:), 256);
size(h)

ans =

     1   256

h2 = conv(h,ones(1,10));
figure
plot(h2)
bin = im>120;
figure
image(bin)
imagesc(bin)
colormap(gray)
diary off