Capturing And Handling Single Image; Image Types - Thermo Scientific Apreo User's Operation Manual

Capturing and Handling Single Image

After acquiring a quality image, it can be paused (F6 or the toolbar icon) and saved (the File menu / Save item).
Setup the file name label and hard drive destination for the image to be saved using the next available label /
number prior to the capture session. Set the databar information important for the archiving by right-clicking on
the image databar.
The conditions for good image quality are:
• Slow scan speed (longer dwell time or fast dwell time together with line or frame integration) of the beam.
• Select a pixel resolution from the drop down list box to suit the detail in the image, i.e. no tearing pixelated edges.
• Move the stage next to the area of interest, increase the magnification at least 2× above the desired value, focus,
correct the astigmatism and lens alignment (using the reduced area), then return the magnification and stage
position back to their desired parameters.
• Use the Videoscope to set the Contrast and Brightness accurately; otherwise use the Auto Contrast Brightness
procedure.
• Use the Pause / Snapshot / Photo / Scanning preset / filtering functions.

Image Types

A computer perceives an image as a two-dimensional array of numbers – a bitmap. Each array element is called a
pixel and is represented as an integer value. Frequently, the pixel is represented as an unsigned 8-bit integer in the
range [0, 255], with 0 / 255 corresponding to black / white and shades of gray distributed over the middle values.
A 16-bit representation produces up to 65 536 different shades of gray (it is not possible to distinguish them
onscreen), which may be crucial for obtaining accurate data in analysis.
The raw scanned image is always a grayscale bitmap. Colors can be added digitally as a result of particular features.
The UI is able to show and save images with various bit depths:
• Grayscale 8 / 16 bit image – offers 256 / 65 536 levels of gray.
Live / Averaged and Integrated images are scanned as 8 / 16 bit ones. For the Mix display images a selection
between the 8 or 16 bit mode is possible.
• Color 24 bit image – offers 256 levels of each primary color (red / green / blue).
Digital colors come from the Display Saturation feature, Enhanced Image module / Color tab, and Mix display
with color mode set to change image bit depth, so the image must be saved as a color one. When the user wants
to acquire the image without these color enhancements, it is necessary to turn off the respective UI functions.
An image can be saved with / without colored digital overlaid graphics (Measurements, Annotations, Patterns,
Videoscope) (see the respective checkbox in the Save As dialog). Other types of overlaid graphics over an image
are never saved (icons, controls, etc.).
Digital File Formats
The image captured can be saved in various
digital formats, depending on the color and
bit depth needed. Generally there is no reason
to save an image with a higher bit and color
depth than what is available in the original
image. Saving an image with a lower bit and
color depth than what is available in the
original leads to a loss of information. In this
case, this message is shown onscreen.
• TIF 8 / 16 file – grayscale only image type,
full data format
• TIF 24 file – color image type, full data
format
A file contains active processing information, which can be utilized for a databar setting.
• JPG file – color image type, compressed data format
A lossy compression algorithm is used, resulting in the smaller file size with a little loss of information. The amount
of loss depends on the particular image appearance and the compression level (factory preset is 80%). The 8 /
24 bit depth is automatically selected when saving a grayscale / color image file.
• BMP file – color image type, full data format. The 8 / 24 bit depth is automatically set when saving the grayscale
/ color image file.
5-36 User Manual
Operating Procedures: Capturing and Handling Single Image
C O N F I D E N T I A L – limited rights
Feb 2018 Revision A