disp_image ( Image : : : )

Displays grey value images.

disp_image displays the grey values of an image in the current output window. The grey value pixels of the definition domain (set_comprise(::'object':)) or of the whole image (set_comprise(::'image':)) are used. Restriction to the definition domain is the default. For the display of grey value images the number of grey values is usually reduced. This is due to the fact that colors have to be reserved for the display of graphics (e.g. set_color) and the window manager. Also depending on the number of bitplanes on the used output device often less than 256 colors (eight bitplanes) are available. The number of "colors" actually reserved for the display of grey values can be queried by get_system. Before opening the first window this value can be modified by set_system. For instance for 8 bitplanes 200 real grey values are the default. The reduction of the number of grey values does not pose problems as long as only grey value information is displayed, since humans cannot distinguish 256 different shades of grey. If certain grey values are used for the representation of region information (which is not the style commonly used in HORUS ), confusions might be the result, since different numerical values are displayed on the screen with the same grey value. The procedure label_to_region should be used on these images in order to transform the label data into HORUS-objects. If images of type 'int2', 'int4', 'real' or 'complex' are displayed, the smallest and largest grey value is computed. Afterwards the pixel data is rescaled according to the number of available grey values (depending on the output device. e.g. 200). It is possible that some pixels have a very different value than the other pixels. This might lead to the display of an (almost) completely white or black image. In order to decide if the current image is a binary image min_max__ can be used. If neccessary the image can be transformed or converted by scale__ and convert_image_type__ before it is displayed.


Attention

If a wrong output mode was set by set_paint, the error will be reported when disp_image is used.


Parameters

Image (input_object)
image -> object
grey value image to display.


Example
/* Output of a grey image: */
read_image(Image1::'affe':) >
disp_image(Image1:::)

Result

If a window is activated, the used image contains valid values and a correct output mode is set, disp_image returns TRUE. Otherwise an exception is raised.


Possible Predecessors

open_window, set_rgb, set_lut, set_hsi, set_window, scale__, convert_image_type__, min_max__


Alternatives

disp_color


See also

open_window, open_textwindow, init_horus, set_comprise, set_paint, set_lut, draw_lut, paint_grey__, scale__, convert_image_type__, dump_pwindow



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