Merge LRGB Images
The Merge LRGB Images command creates an RGB
color image by merging 3 separate images interpreted as the red,
green, and blue channel data plus a 4th image that represents
luminance devoid of color information. The source images are taken
from an
Image Set opened in the source Image Window. The
resulting RGB image is opened in a new
Image Window.
The merging process uses parameters adjusted in a
docking pane attached to the
Image Window. This process is essentially a matter of
choosing the black level and white level for each of the channel
images, hence the docking pane includes several controls for
setting these levels for the component images. The picture below
shows the Merge LRGB pane opened for a window containing
several of the sample images.
Overview
The strategy behind this command is to adjust the
minimum pixel value and maximum pixel value for the channel images.
For merging the channel images, these values correspond to the
values that will become the black and "white" (or maximum color)
levels, respectively. Setting the minimum and maximum pixel values
effectively changes the contrast and brightness of each channel in
the merged RGB image.
The values in the text fields are used for merging,
regardless of how they are set. Beyond simply typing a number into
each text field, several controls are provided for setting these
values.
The following table shows several ways to adjust
the minimum and maximum pixel values for the R channel image. These
same controls are provided for all four channels.
Controls for Setting Merge Values for the Red
Channel Image
|
|
Select the source image from the image set.
|
|
Automatically set the trackbar limits using
minimum and maximum pixel values from the image histogram.
|
Minimum Value
|
|
|
Shows the minimum value for merging. It may be
entered by typing.
|
|
Calculate the minimum value (black limit) from
statistics inside the
Image Cursor. This sets the limits for the
trackbar.
|
|
Adjust the minimum value using the trackbar
|
Maximum Value
|
|
|
Shows the minimum value for merging. It may be
entered by typing.
|
|
Calculate the maximum value (white limit) from
statistics inside the
Image Cursor. This sets the limits for the
trackbar.
|
|
Adjust the maximum value using the trackbar
|
In an LRGB image, the R, G, and B channels
contribute the color information while the Luminance (L channel)
image contributes signal. The L image is usually an unfiltered
image having high signal-to-noise ratio. The nature of human color
perception makes it so the luminance channel image can be sharpened
to show sharper detail in the output image without incurring the
grainy effect of sharpening the color channel images. Conversely,
the color channel images are of lower signal to noise ratio and
they may be
de-speckled to remove color channel noise without
making the merged image appear more blurry. The Luminance image is
usually merged in at a percentage level so that it does not
overwhelm the color channel data. Often a Luminance % setting in the range of 15 to 40% is
appropriate.
The [Merge] button
scales each of the images using minimum and maximum values from the
text fields. The Auto Merge check box
enables automatic merging after changing any of the six trackbars.
When the channels are merged, Mira creates the new RGB image in a
new
Image Window. If the images are merged again, the new
RGB image overwrites the previous RGB image in the window. The
final color brightness, contrast, and color balance of the RGB
image can be refined using the
Palette Properties dialog for the output window.
The [Save] and
[Reset] buttons save and re-load the
parameters below the horizontal line.
Procedure for Merging Images
-
Open the images to be used for the R, G, B, and
L channels as an
Image Set in an
Image Window. Make sure this source window is on
top.
-
From the Image Window's Process > LRGB
Images menu, click Merge LRGB
Images to open the docking pane into the source window.
-
Select the output type as 24-bit or 48-bit.
-
Select channel images from the image set using
the R, G, B, and L channel drop lists.
-
Adjust the Min
Value and Max Value for each
channel using the controls in the docking pane.
-
Click [Merge] to
combine the channel images. The RGB image will open in a new
Image Window.
-
Tip: The
Auto Merge checkbox
causes the channel images to be re-merged immediately after
adjusting the trackbar or pressing Enter for a text field.
-
If the brightness, contrast, or color balance
need to be changed, repeat steps 5 through 7. Repeat steps 4
through 7 if you need to select different channel images.
Related Topics
Working with RGB Images
Merge RGB Images
Extract Channel
Mira Pro x64 8.71 User's Guide, Copyright Ⓒ 2024 Mirametrics, Inc.
All Rights Reserved.
|