IMAGE_CREATE Function
Creates an image associative array. Refer to IMAGE_READ Function for a list of supported file types.
Tip: If you have 64-bit PV‑WAVE and need to read and write images up to 32-bits without constraints on data size, use the PHOTO OPI routines.
Usage
image = IMAGE_CREATE(pixel_array)
Input Parameters
pixel_array—An array containing image data. The input array must be in one of the following forms, where w is the image width, h is the height, and img_count, an optional parameter, is the number of images in the array:
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(w, h[, img_count])—8-bit (pseudo-color) images
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(3, w, h[, img_count])—24-bit (RGB) images, pixel interleaved
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(w, 3, h[, img_count])—24-bit (RGB) images, row interleaved
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(w, h, 3[, img_count])—24-bit (RGB) images, image interleaved
Returned Value
image—An image associative array.
Keywords
Colormap—A 3-by-n colormap array.
| Note: If the input pixel_array is 2D and the Colormap keyword is not specified, the returned image is assumed to be grayscale. |
Colormodel—A long integer specifying the color model:
-
0—Monochrome or gray scale
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1—RGB
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2—CMY (Currently not supported)
-
3—HSV (Currently not supported)
Comments—A string containing additional information about the image. This feature is supported for GIF, JPEG, MIFF, PNG, TGA, and TIFF formats.
Depth—A long integer specifying the number of bits per channel. (Default: 8)
File_Name—A string containing a default filename for the image.
File_Type—A string specifying the type of image file to create. For example, 'sun' denotes a Sun Rasterfile. (Default: TIFF)
| Note: Refer to IMAGE_READ Function for a list of valid file types. |
| Note:
If File_Type is set to ‘DICM’, IMAGE_CREATE adds the following File Meta Information and DICOM tags to the ‘comments’ key of the image associative array:
|
Getcolormap—When specified IMAGE_CREATE uses the current colormap.
| Note: The Colormap and Getcolormap keywords are mutually exclusive and cannot be used in the same call to this function. |
Img_Count—A long integer specifying the number of images in the output array image. (Default: 1)
Intleave—A scalar STRING indicating the interleaving of the pixel array when it cannot be determined by examining the pixel array itself.
PV‑WAVE attempts to determine the interleaving of the pixel array by locating the smallest dimension. In cases where this is ambiguous, for example the pixel data has multiple dimensions of size '3' or the height and/or width of the image is less than '3', PV‑WAVE may fail to create the image. In these cases, use the Intleave keyword to indicate to PV-WAVE what the interleaving of your pixel array is.
Valid strings and the corresponding interleaving methods are:
'image'—The RGB pixel array arrangement is (x, y, 3) for 3 image-interleaved channels of x-by-y pixels.
'row'—The RGB pixel array arrangement is (x, 3, y) for 3 row-interleaved channels of x-by-y pixels.
'pixel'—The RGB pixel array arrangement is (3, x, y) for 3 pixel-interleaved channels of x-by-y pixels.
Quiet—Suppresses successive levels of error messages, depending on the value set. This keyword accepts the same integer values used with the system variable !Quiet.
Units—Units of pixel size. (1 = inches; 2 = millimeters)
X_resolution—Pixel size in Units.
Y_resolution—Pixel size in Units.
Discussion
The IMAGE_CREATE function creates an image associative array. Complete image information is stored in this type of array, which is used by all of the IMAGE_* routines in PV‑WAVE. (Refer to the PV‑WAVE Programmer’s Guide for additional information on associative arrays.)
| Note: When creating an image that contains 3D pixel data, you must specify the interleaving method if either the width or height has a value of 3 or less. For example, if the dimensions of your data are 100 × 3 × 3 and the data is image interleaved, it could be interpreted incorrectly unless you explicitly set the Interleave keyword to the correct interleaving method. |
The image associative array allows the following operations:
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File I/O of images to and from different file formats
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Displaying images
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Processing images
Image Associative Array Structure
Image Associative Array’s Keys describes each key of the image associative array.
|
Array Key Name |
Variable Type |
Description |
|
file_name |
STRING |
Absolute or relative pathname of an image file |
|
file_type |
STRING |
The type of image file. (See IMAGE_READ for a list of supported file types.) |
|
width |
LONG |
Image width |
|
height |
LONG |
Image height |
|
img_num |
LONG |
Index number in the range {0...n} of a subimage in the file (if the image was created with IMAGE_READ) |
|
img_count |
LONG |
Number of subimages in the pixel array |
|
PIXELS: |
||
|
nr_cc |
LONG |
Number of color channels. This item specifies how many storage units are allocated per pixel. (Supported values: 1 and 3) |
|
depth |
LONG |
Bits per color channel |
|
pixel_dtype |
LONG |
Data type of the pixel array: 1 = BYTE 2 = INT ** 3 = LONG ** 13 = INT32** |
|
interleave |
LONG |
Interleave method used: 1 = Pixel interleaving 2 = Row interleaving 3 = Image interleaving |
|
color_model |
LONG |
Color model: 0 = Monochrome or gray scale 1 = RGB 2 = CMY (currently not supported) 3 = HSV (currently not supported) |
|
pixels |
BYTE |
A multidimensional array describing an 8-bit or 24-bit image. Refer to the Pixel Arrays section later for a description of supported pixel arrays. |
|
x_resolution |
FLOAT |
Pixel size in units |
|
y_resolution |
FLOAT |
Pixel size in units |
|
units |
LONG |
Units of pixel size: 1 = (inches) 2 = (mm) |
|
COLORMAP: |
||
|
cmap_type |
LONG |
Type of colormap: 0 = No colormap 1 = 1 colormap vector (not supported) 2 = Multiple colormap vectors |
|
cmap_dtype |
LONG |
Data type of colormap (only BYTE (1) is supported) |
|
n_colors |
LONG |
Number of entries in the colormap |
|
colormap |
BYTE |
Array whose dimensions depend on cmap_type and n_colors. cmap_type: 1 = not supported 2 = (3 , n_colors) |
|
SUPPLEMENTARY and CONTROL: |
||
|
label |
STRING |
Optional annotation (Note: None of the supported graphics file types currently support labels.) |
|
comments |
STRING |
Optional information about source, etc. |
|
status |
LONG |
0 = success; < 0 = error |
|
** This data type is currently not supported for IMAGE_READ and IMAGE_WRITE. IMAGE_CREATE accepts an array in this data type, but before writing the image to a file the pixel array must be converted to BYTE. |
||
Pixel Arrays
Valid Pixel Arrays describes valid pixel arrays.
|
Color Model |
Color Channels, Number (nr_cc) |
Bits per pixel |
Colormap |
Color Channels in Colormap, Number |
Dimensions, pixel array |
|
RGB |
3 |
24 |
Optional |
3, if colormap present |
|
|
GrayScale |
1 |
8 |
Yes |
3 |
2D ** |
|
Pseudo Color |
1 |
8 |
Yes |
3 |
2D ** |
|
** Refer to the Pixel Array Dimensions table for more information. |
|||||
Pixel Array Dimensions
Pixel Array Dimensions describes the valid pixel array dimensions. The dimensions of the pixel array (width, height, nr_images, etc.) refer to keys in the image associative array.
|
Type of Array |
Description |
|
2D Pixel Arrays: |
|
|
(width, height[, nr_images]) |
8-bit (pseudo-color) image |
|
3D Pixel Arrays: |
|
|
(nr_cc, width, height[, img_count]) |
24-bit (RGB) image, pixel interleaved |
|
(width, nr_cc, height[, img_count]) |
24-bit (RGB) image, row interleaved |
|
(width, height, nr_cc[, img_count]) |
24-bit (RGB) image, image interleaved |
Example 1
This example demonstrates how IMAGE_CREATE creates an image associative array. The associative array is listed using the INFO command.
; Create some pixel data (all zeros). pixels = BYTARR(100, 200) ; Create a colormap (all zeros). cmap = BYTARR(3, 50) ; Create the image associative array. Next, use ; INFO to display the contents of the array. image = IMAGE_CREATE(pixels, File_name='test.tif', $ Colormap=cmap, File_type='tif') INFO, image, /Full
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Example 2
; Make up some unsigned 16-bit data and put it in a long array.
img = IMAGE_READ(!Dir + '/demo/gallery3/data/veggies.jpg')
img = SCL(img('pixels'), 65535, /Long)
WINDOW, Xsize=800
TVSCL, img
; Write a 16-bit tiff file.
status = IMAGE_WRITE('image_create_ex2.tif', $
IMAGE_CREATE(img, Comments='little', Depth=16))
; Read it back in.
new_img = IMAGE_READ('image_create_ex2.tif', File_type='tiff16')
INFO, new_img, /Full
TVSCL, new_img('pixels'), 400, 0
See Also
IMAGE_DISPLAY, IMAGE_READ, IMAGE_WRITE
System Variables: !Quiet
