一、Using Offset Correction
The offset correction of images should be used to eliminate the effects of pixel dark currents on the acquired image.To obtain an Offset correction file:
1 Select the desired integration time, readout mode, and gain setting.
2 Switch off the X-ray source so that the detector only transfers its “dark image.”
3 Wait a few seconds until the detector achieves equilibrium.
4 Start the Get Offset Image/Start All Offset Images Select a number of frames.We recommend you use between 20 and 100 frame cycles, which will be averaged. The averaged
image is qualified as the new Offset Image of the selected frame time and automatically linked to later acquired images.
5 Control the new acquired image using the Options/View command and/or Brightness, Contrast or LUT range.
6 Save the Offset correction file, if desired.
二、Using Single/Multiple Gain Correction
The Gain Correction is used to eliminate the effects of pixel sensitivities and the X-ray source on
the acquired image.To obtain a Multiple Gain Correction file:
1 Select the desired integration time, readout mode, and gain setting
2 Acquire a new Offset correction image.
3 Switch on the X-ray source and adjust the brightness of the acquired image in the desired readout settings. The detector’s acquired intensity should be in the dynamic range of the ROI. The whole image should be illuminated homogenously.
4 Start the Acquire Sequence.
5 Select a number of frames and the average mode.20 to 100 frame cycles should be used, which will be averaged.
6 Store the Offset corrected bright image.
7 For Multiple Gain Correction, repeat the steps 3-6 for all signal intensities of interest. Up to 10 gain images can be used for the Multi Gain Correction (MGC).
8 Create the Gain –Sequence of all Bright Images with Acquire=>Build Gain Sequence using the Acquire > Build Gain sequence.”
9 Start a new acquisition.
10 Link the created Gain-Sequence file with Acquire=>Link Gain Sequence.
11 Store the Gain correction file, if desired.
三、Using and Generating Pixel Correction
The Pixel Correction of images is used to eliminate the effects of underperforming pixels of the detector on acquired images. To get a Pixel correction file:
1 Select the desired frame time (see the Timings menu).
2 Link correction files.
3 Switch on the X-ray source and start the continuous mode.The detector’s acquired intensity should be about 70-80% of its maximum signal.
4 Start an image acquisition as for the Get Gain/Offset Image (no sample in front of the detector).
5 Adjust the new acquired image by using the Options/View command and/or Brightness, Contrast, or Look up Table (LUT) range. The window should show a homogenous corrected image. Intensity deviations are the result of marginal pixels.
6 Adjust the X-ray source so that the detector’s acquired intensity is about 30-40% of its maximum signal.
7 Acquire an average image of 20-100 frames.
8 From the Edit menu, select Value.
9 Enter the desired range of good pixels (for example, +/- 10% around the selected grey value).
10 Click the Out of range button.All selected pixels are marked.
11 From the Edit menu, choose Create Pixel Map. The Pixel Map is created and can be stored as new PXLMASK.HIS.
四、Correcting Previously Acquired Images
You can correct previously acquired uncorrected images by selecting the desired image using the Window Command and a Link Command (Link Offset Correction, Link Gain Correction, or Link Pixel Correction). The active image is automatically corrected. These settings are also used for the next acquisitions.