Chapter 2
Getting Measurement-Ready Images
©
National Instruments Corporation
2-3
IMAQ Vision for Visual Basic User Manual
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Complex
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32-bit RGB
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32-bit HSL
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64-bit RGB
When you create an image, it is an 8-bit image by default. You can set the
Type
property on the image object to change the image type.
When you create an image, no memory is allocated to store the image
pixels. IMAQ Vision methods automatically allocate the appropriate
amount of memory when the image size is modified. For example, methods
that acquire or resample an image alter the image size, so they allocate the
appropriate memory space for the image pixels.
Most methods belonging to the IMAQ Vision library require an input of one
or more image objects. The number of images a method takes depends on
the image processing function and the type of image you want to use.
IMAQ Vision methods that analyze the image but do not modify the image
contents require the input of one source image. Methods that process the
contents of the image require one or more source images and a destination
image. Exceptions to the preceding statements are methods that take a mask
image as input.
The presence of a
MaskImage
parameter indicates that the processing or
analysis is dependent on the contents of the mask image. The only pixels
in the source image that are processed are those whose corresponding
pixels in the mask image are non-zero. If a mask image pixel is 0, the
corresponding source image pixel is not processed or analyzed. The mask
image must be an 8-bit image.
If you want to apply a processing or analysis method to the entire image,
do not supply the optional mask image. Using the same image for both the
source image and mask image also has the same effect as not using the
mask image, except in this case the source image must be an 8-bit image.
Most operations between two images require that the images have the same
type and size. However, arithmetic operations work between two different
types of images. For example, an arithmetic operation between an 8-bit
image and 16-bit image results in a 16-bit image.
