[[uvscada:gxs700]]
 
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uvscada:gxs700 [2017/12/23 18:27] – [Force capture] mcmasteruvscada:gxs700 [2017/12/31 19:19] – [Calibration] mcmaster
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 ^ Image  ^ Vendor  ^ Product                ^ Works?    ^ Notes                                                    ^ ^ Image  ^ Vendor  ^ Product                ^ Works?    ^ Notes                                                    ^
-|        | Gendex  | GXS700 small (type 1)  | Yes*      | Linux VM problematic from Windows VMWare and VirtualBox  |+|        | Gendex  | GXS700 small (type 1)  | Yes       | Linux VM problematic from Windows VMWare and VirtualBox  |
 |        | Gendex  | GXS700 large (type 2)  | Yes       | Primary device I develop for                             | |        | Gendex  | GXS700 large (type 2)  | Yes       | Primary device I develop for                             |
 |        | Dexis   | Platinum               | Probably  | Test failed but DUT was likely broken                    | |        | Dexis   | Platinum               | Probably  | Test failed but DUT was likely broken                    |
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 {{:uvscada:gxs700:good.png?300}} {{:uvscada:gxs700:good.png?300}}
  
-    - $ python gxs700/capture.py -f+    - $ python gxs700/capture.py -f -e
     - Check which you got:     - Check which you got:
       * Waiting for image: expected response.  Continue below       * Waiting for image: expected response.  Continue below
       * "Exception: Failed to find a device": plugged in?  Did you run permission script?       * "Exception: Failed to find a device": plugged in?  Did you run permission script?
-    - It should have written capture_000.png and capture_000.bin to the current directory +    - It should have written capture_000_e.png to the current directory 
-    - Above will be very dark.  Enhance contrast by doing histogram equalization: python gxs700/decode.py -e capture_000.bin capture_000e.png +    - You should see an image roughly resembling the noise of the reference above.  If you do, your sensor probably works
-    - You should see an image roughly resembling the reference above.  If you do, your sensor probably works+
  
 ====== X-ray capture ====== ====== X-ray capture ======
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 Takes raw, uncalibrated images.  I've been asked a few times if I could provide calibration files for the Windows driver or could even use their calibration files on my driver.  However, I'm not really interested in supporting their proprietary format. If someone submits a patch though I'll probably merge it in. Takes raw, uncalibrated images.  I've been asked a few times if I could provide calibration files for the Windows driver or could even use their calibration files on my driver.  However, I'm not really interested in supporting their proprietary format. If someone submits a patch though I'll probably merge it in.
  
-That said, I'm not against coming up with an independent calibration scheme.  I know how to take dark frames (see API) which is the key component.  Uncalibrated images have been generally good enough for me so I haven't put work into this.  If you are interested though shoot me a line.+===== cal.py flow ===== 
 + 
 +Quick scheme to get rid of the worst artifacts 
 + 
 +Basic idea: 
 +  - Capture a dark field frame (no x-ray) to get the lowest possible pixel value 
 +  - Capture a flat field frame (x-ray with no object) to get the highest possible pixel value 
 +  - Rescale images to range found above 
 + 
 +Notes: 
 +  * Decoded images invert pixel values (per x-ray industry convention), so high and low are relative 
 +  * As of late 2017 capture.py now spits out a sensor .json file with each image. Hopefully the scanner will add this soon as well 
 +  * As of this writing no bad pixel replacement is done 
 + 
 + 
 +==== 1: Capture dark field ==== 
 + 
 +First, take a dark field capture using something like: 
 + 
 +  $ gxs700-capture -f -e 
 + 
 +This should yield a raw picture that looks something like this: 
 + 
 +{{:uvscada:gxs700:cal:df.jpg?300|}} 
 + 
 +And histogram equalized looks like this: 
 + 
 +{{:uvscada:gxs700:cal:dfe.jpg?300|}} 
 + 
 + 
 +==== 2: Capture flat field ==== 
 + 
 +Now make sure the sensor and the x-ray head have the exact same position and settings you will use to take your actual image capture. Make sure there is nothing in the beam and do a standard capture (and also firing the x-ray head): 
 + 
 +  $ gxs700-capture -e 
 + 
 +This produces a flat field image like this: 
 + 
 +{{:uvscada:gxs700:cal:ff.jpg?300|}} 
 + 
 +Which might look like this when histogram equalized: 
 + 
 +{{:uvscada:gxs700:cal:ffe.jpg?300|}} 
 + 
 +For best results you should also let the sensor and x-ray head sit a while to warm up. I'm not sure how long matters, but maybe 10 minutes would be good 
 + 
 + 
 +==== 3: Capture data ==== 
 + 
 +ie using capture.py or xray_plan_cli.py 
 + 
 +Put your sample in and use the exact setup as the flat field to capture data. Don't move the sensor or x-ray head 
 + 
 + 
 +==== 4: Correct images ==== 
 + 
 +run something like 
 + 
 +  $ python cal.py  df.png ff.png png cal 
 + 
 +Where: 
 +  * df.png is your dark field capture 
 +  * ff.png is your flat field capture 
 +  * png is a directory with your images to be corrected 
 +  * cal is the output directory with corrected images 
 + 
 +Here is a raw image as captured: 
 + 
 +{{:uvscada:gxs700:cal:ex_raw.jpg?300|}} 
 + 
 +And with histogram equalization: 
 + 
 +{{:uvscada:gxs700:cal:ex_raw_e.jpg?300|}} 
 + 
 +Now the corrected image: 
 + 
 +{{:uvscada:gxs700:cal:ex_out.jpg?300|}} 
 + 
 +And it with histogram equalization: 
 + 
 +{{:uvscada:gxs700:cal:ex_out_e.jpg?300|}}
  
 ====== Quality ====== ====== Quality ======
 
 
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