Mitsubishi P91DW User Manual download pdf (Page 171)

Alpha Innotech User’s Manual, version 4

5-70

The INVERT function reverses the gray scale assignments so that 0 corresponds to white

and 4,095 corresponds to black.

If the image has dark bands and light background, then INVERT should be selected

by placing an “X” in its box. If the image has light bands and dark background, the

INVERT option should not be activated.

Unlike the REVERSE button described in Chapter 2, this function does not alter the

appearance of the image.

Calculating Background Values:

Background subtraction is an important part of image densitometry analysis. There are

three background subtraction options in the Spot Density tools.

IDV = ∑ (each pixel value - BACK)

No Background

If no background calculation method has been selected, the background value in the data

window (BACK) is reported as zero (0). Therefore, the object’s integrated density value

will be equal to the sum of all the pixel values within the box, ellipse, or freehand

drawing. Recommendation: No Background or Manual Background is suggested for

AutoSpot, Magic Wand (only the border outlines though) or any object where little if any

background is included in the object area of interest.

Automatic Background

When the AUTO BACKGRD function is active (an “X” appears in the checkbox),

AlphaEaseFC determines the average of the 10 lowest pixel values in each individual

object and assigns that value to BACK. This option is useful if the image has regions

with different background levels, because the background values (BACK) will be unique

for each object.

Spot Denso Toolbox Showing Auto Background Active

Note: If AUTO BACKGROUND is active, it will override the manual background

option (described below).

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Mitsubishi P91DW User Manual Page 171