A capture Parameter-Set consists of the following information: lighting-intensity for the 4 LEDs, and the camera’s exposure, gain and focus values. These values are applied prior to capturing a rackimage containing barcodes to be decoded. Up to 12 Parameter-Sets can be defined for each rackprofile. These combinations are set by users using various Camera and LED functions. Typically, a profile requires only one Parameter-Set to decode completely from images captured with that parameter-set alone. However, certain types of racks may not be easily decoded using one setting (such as those with low contrast, suboptimal printing, reflective or curved surfaces, or sensitive to lighting). For such racks, 2nd or 3rd Parameter-sets may be appended to the profile, so that if decoding was incomplete with one set of settings, the Decoder will automatically apply the next setting in attempt to decode the remaining tubes, and so on. If all parameter-sets have been tried without 100% success, SCAN SDK will loop back to fetch the first set, and the process continues until either all barcodes are decoded, a user-specified Timeout occurred, or decoding is stopped by calling S_StopDecode.
Each Parameter-Set contains the following image capture settings:
- Camera’s Focus
- Intensity levels of LED1 through LED4
- Camera’s Gain
- Camera’s Exposure
Sample content of a rack’s profile with 2 Parameter-sets:
{
"General" :
{
"Embedded" : 1,
"Footprint" : "S",
"Name" : "DEMO96-E",
"Quadcode" : false
},
"Grid" :
{
"EmbOffsetX" : 2450,
"EmbOffsetY" : 284
"EmbRadius" : 100,
"EmbSizeX" : 144,
"EmbSizeY" : 137,
"NumCols" : 12,
"NumRows" : 8,
"OffsetX" : 260,
"OffsetY" : 137,
"Radius" : 100,
"SizeX" : 2477,
"SizeY" : 1661
},
"ParameterSets" :
[
{
"Exposure" : 7610.135,
"Focus" : 155,
"Gain" : 1.36,
"Led1" : 128,
"Led2" : 128,
"Led3" : 128,
"Led4" : 128
},
{
"Exposure" : 15191.113,
"Focus" : 162,
"Gain" : 1.84,
"Led1" : 96,
"Led2" : 96,
"Led3" : 96,
"Led4" : 96
}
]
}
The next screen shot shows image resulted from applying the first Parameter-set (index 0). Note:
the screen shot is captured from WpfDemo, a C# sample project included with the setup of this
SDK.
{
"Exposure" : 7610.135,
"Focus" : 155,
"Gain" : 1.36,
"Led1" : 128,
"Led2" : 128,
"Led3" : 128,
"Led4" : 128
}
While the Focus value of 155 produces sufficiently sharp images for regular tubes, it captured a
blurry image of the embedded barcode which will likely cause decoding to fail.
If decoding fails to complete due to the blurry image produced by applying the first Parameter-set, a new image will be captured after applying the next Parameter-set (index 1):
{
"Exposure" : 15191.113,
"Focus" : 162,
"Gain" : 1.84,
"Led1" : 96,
"Led2" : 96,
"Led3" : 96,
"Led4" : 96
}
The Focus value of 162 in the 2nd Parameter-set (in combination with other elements in the set)
captures a better embedded barcode image, and helps completing the decoding process of all 97
barcodes.
Note that most tube racks would require only 1 Parameter-set to decode all barcodes. Only use a
multiple Parameter-set profile if a single Parameter-set cannot be configured to decode all tubes
after multiple captures. The above profile is designed for illustration purpose only. In reality, the
2nd Parameter-set could be used as the lone Parameter-set in a single Parameter-set profile to
decode all barcodes in the rack.
See Labware Profile and Parameter-Sets for the list of functions Scan SDK provides to create and manage labware profiles.