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Image Acquisitionand Proces

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4 <strong>Image</strong> Acquisition <strong>Proces</strong>sing with LabVIEW<br />

antialiased edges, and the ability to paste the image over a background with the<br />

foreground information seemingly blending in. Generally, this form of transparency<br />

is of little use to the industrial vision system user, so the Vision Toolkit ignores all<br />

forms of a information.<br />

The size of color images follows the same relationship as grayscale images, so<br />

a 1024 ¥ 768 24-bit color image (which equates to a 32-bit image including 8 bits<br />

for the alpha channel) would require the following amount of memory:<br />

MemoryRequired = 1024 ¥ 768 ¥ 32<br />

= 25165824 Bits<br />

= 3145728 Bytes<br />

= 3.072 MBytes<br />

1.1.3 COMPLEX<br />

Complex images derive their name from the fact that their representation includes<br />

real and complex components. Complex image pixels are stored as 64-bit ßoatingpoint<br />

numbers, which are constructed with 32-bit real and 32-bit imaginary parts.<br />

Pixel Depth<br />

Channel Intensity Extremities<br />

Real (4 bytes) Imaginary (4 bytes) –2147483648 to 2147483647<br />

A complex image contains frequency information representing a grayscale<br />

image, and therefore can be useful when you need to apply frequency domain<br />

processes to the image data. Complex images are created by performing a fast Fourier<br />

transform (FFT) on a grayscale image, and can be converted back to their original<br />

state by applying an inverse FFT. Magnitude and phase relationships can be easily<br />

extracted from complex images.<br />

1.2 FILE TYPES<br />

Some of the earliest image Þle types consisted of ASCII text-delimited strings, with<br />

each delimiter separating relative pixel intensities. Consider the following example:<br />

0 0 0 0 0 0 0 0 0 0 0<br />

0 0 0 125 125 125 125 125 0 0 0<br />

0 0 125 25 25 25 25 25 125 0 0<br />

0 125 25 25 255 25 255 25 25 125 0<br />

0 125 25 25 25 25 25 25 25 125 0<br />

0 125 25 25 25 255 25 25 25 125 0<br />

0 125 25 255 25 25 25 255 25 125 0<br />

0 125 5 25 255 255 255 25 25 125 0<br />

0 0 125 25 25 25 25 25 125 0 0<br />

0 0 0 125 125 125 125 125 0 0 0<br />

0 0 0 0 0 0 0 0 0 0 0

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