Andor iQ USER GUIDE

Andor iQ USER GUIDE

5.1 Image Contrast and LUTs

Selecting the View menu item provides the necessary tools for the adjustment of image contrast and brightness and selection of look up tables (LUTs).

5.1.1 LUT Control and Creation

The LUT function is accessed from the View menu as described above. Clicking the right mouse button while the cursor is on the

Channel Icon below the image will also open up a pop-up menu with three entries: LUT, Mapping and Auto-Map. Mapping opens up the Image Contrast Dialogue as described above. The Auto-Map option has the same functionality as the Automap button discussed above. LUT opens up a selection of pre-defined Palettes or Look

Up Tables (LUTs), some of which are listed below:

Grey

– In the Grey level Palette each image pixel grey value is represented by equal weights of red, green and blue components. Thus, black (grey level 0) has 0, 0, 0.

White (grey level 255) has 255,255,255. This is a standard method of visualizing

monochrome images.

Negative - The inverse of grey Palette, where black appears white and vice-versa.

Obtained by the "1's complement" of image grey levels.

Camera - An input Palette from a camera, where intensity is proportional to the video

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Andor iQ USER GUIDE signal level, i.e. this is a normal grey scale. However, grey level zero (black) is set to

RED=255, B=G=0, while grey level 255 (white) is set to GREEN=255, R=B=0). Use this Palette when setting up imaging conditions to detect when saturation occurs.

Red - This is a monochrome palette using only the Red color component (intensity

255 - the maximum color brightness). This provides an image shown in a manner that may be reminiscent of viewing a fluorescent image with the appropriate fluorochrome.

Green - This is a monochrome palette using only the Green color component

(intensity 255 - the maximum color brightness). This provides an image shown in a manner that may be reminiscent of viewing a fluorescent image with the appropriate fluorochrome.

Blue - This is a monochrome palette using only the Blue color component (intensity

255 - the maximum color brightness). This provides an image shown in a manner that may be reminiscent of viewing a fluorescent image with the appropriate fluorochrome.

Bandit - A color-banded Palette, ("the banded one") in which groups of 16 grey

levels are visualized as the same color. This is useful for pseudo-coloring and for visualizing and enhancing structural and intensity variation in images. This is valuable for comparing changes to the image after a processing operation.

Furnace - This Palette is a yellow-brown table in which intensity is matched to

brightness along the yellow-brown color scale. Furnace provides enhancement to the visibility of low contrast image structure.

If none of the above palettes are selected the default palette is used.

At the bottom of the LUT list, there are three options available: Load, Edit and Save.

The user can load a previously defined LUT by selecting the Load option. This will

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Andor iQ USER GUIDE open up an Open File Dialog and the user can select the LUT files they want. When

Edit is selected, an Edit LUT Dialog is displayed from which the user can modify the

current LUT by adjusting the graphic presentations of its Red, Green and Blue components.

The modified LUT can be saved as a new one if Save is selected later. The LUT pop-up list will show add user-defined LUTs to its List once they have been saved.

Another way of creating new LUTs is from a text file based exactly on the format of the LUT file. The LUT file format is illustrated over.

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FORMAT of LUT FILE:

[Description]

ASCII LUT File=TRUE

[Red Green Blue]

000=000 000 000

001=000 001 000

002=000 002 000

003=000 003 000

004=000 004 000

005=000 005 000

006=000 006 000

007=000 007 000

008=000 008 000

009=000 009 000

……..

250=000 250 000

251=000 251 000

252=000 252 000

253=000 253 000

254=000 254 000

255=000 255 000

You can create this in Notepad or you favorite editor and then save the file to the

LUT folder, which can be found here: C:\Documents and Settings\All

Users\Application Data\Kinetic Imaging\Configuration\LUT

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Andor iQ USER GUIDE

5.1.2 Image Contrast Control

The Mapping and Automap options have the same functionality as the Mapping and

Automap buttons described previously in Section 2.8.1.

Selecting the Mapping menu item displays the dialogue illustrated above.

To invert the mapping (flip contrast) check the Invert option.

The scale of the mapping mode can exclude certain areas if the Exclude checkbox is enabled.

Selecting “View->Log Scale Histogram” transforms the histogram Y axis to a logarithmic scale, emphasizing the low frequencies

Selecting “View->Zoom To Map” scales the histogram X axis around the Min-Max values, as shown opposite.

From the drop down list below the Mapping Range scrollbars, you can select the required mapping mode (e.g. Gamma, Square, Square Root, Sine, Cosine, Log e,

Log 10, Exp e, Exp 10 and Linear). The diagram below illustrates the various mapping modes that are available.

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Andor iQ USER GUIDE

Gamma is the default mapping and generates a mapping of the form, , where

Gamma has the range 0.1 to 8.0. This gives the user ultimate flexibility in enhancing

images. Gamma = 1 is linear, 0.5 is square root and 2.0 is square. Users can control the gamma coefficient value using the slider or the text box.

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