Methods and apparatus for low resolution item identification
View Patent ↗Methods and apparatus are provided for low resolution item identification. An image of an unknown item is captured and quantized to greatly lower the resolution of the image. The quantized image data of the unknown item is compared to a plurality of the quantized image data for known items. The comparison includes using a signal-to-noise ratio calculated using the quantized image data for both the unknown and known items. A match is found when the calculated signal-to-noise ratio is above a predetermined threshold value.
1. A computer implemented method to identify an unknown item presented to an optical code scanner based on the appearance of the item, the method comprising:
capturing a digital image of the unknown item by the optical code scanner;
quantizing the captured image to reduce the amount of data that represents the image of the unknown item; and
comparing the quantized image data for the unknown item to a plurality of quantized image data for known items where the comparing includes using a calculated signal to noise ratio (SNR) between the unknown and known quantized image data to determine when a match is found between the unknown item and a known item.
2. The method of claim 1 , wherein the quantizing includes performing a pixelation on captured image data to reduce the size of original image data.
3. The method of claim 1 , wherein the comparing includes calculating a root-mean-square (RMS) for the quantized image data of the unknown item.
4. The method of claim 3 , wherein the comparing further includes generating variance image data where the variance image data is the difference between the quantized image data of the unknown item and quantized image data for the known item.
5. The method of claim 4 , wherein calculating the SNR includes calculating a “signal” value which is the RMS value of the quantized image data of the known item and calculating the “noise” value which is the RMS value of the variance image data and the value for the SNR is calculated by dividing the “signal” value by the “noise” value.
6. The method of claim 5 , wherein a predetermined threshold SNR value is used to determine a minimum confidence level that can be used to determine that the match has been found.
7. The method of claim 5 , wherein within the quantized image data for both the known and unknown items, the data for each pixel is reduced to include data for only one color.
8. The method of claim 1 , wherein the plurality of quantized image data for known items are stored in a database.
9. The method of claim 8 , wherein the database is stored in the optical code scanner.
10. The method of claim 8 , wherein the database is a customized database and accepts the quantized image data for the unknown item and performs the comparison to the quantized image data for the known items stored in the database and returns the known item that matches the unknown item.
11. The method of claim 1 , further including selecting the plurality of quantized image data for known items from a larger set of quantized image data for known items using one or more physical attributes of the unknown item.
12. The method of claim 1 , wherein the quantizing reduces the number of pixels represented in the captured image data down to fewer than 200 pixels.
13. The method of claim 1 , wherein there are multiple quantized images for each known item where at least one quantized image was generated from an image taken of the front of the item and at least one quantized image was generated from an image taken of the back of the item.
14. An optical code scanner comprising:
an image capture device;
a memory including computer instructions; and
a processor in communications with the image capture device and the memory where the computer instructions when executed by the processor cause the processor to perform functions including:
capturing a digital image of the unknown item by the image capture device;
quantizing the captured image to reduce the amount of data that represents the image of the unknown item; and
comparing the quantized image data for the unknown item to a plurality of quantized image data for known items where the comparing includes using a calculated signal to noise ratio (SNR) between the unknown and known quantized image data to determine when a match is found between the unknown item and a known item.
15. The optical code scanner of claim 14 , wherein the quantizing includes performing a pixelation on captured image data to reduce the size of original image data.
16. The optical code scanner of claim 15 , wherein the comparing includes calculating a root-mean-square (RMS) for the quantized image data of the unknown item.
17. The optical code scanner of claim 15 , wherein the comparing further includes generating variance image data where the variance image data is the difference between the quantized image data of the unknown item and the quantized image data for the known item.
18. The optical code scanner of claim 17 , wherein calculating the SNR includes calculating a “signal” value which is the RMS value of the quantized image data of the known item and calculating the “noise” value which is the RMS value of the variance image data and the value for the SNR is calculated by dividing the “signal” value by the “noise” value.
19. The optical code scanner of claim 18 , wherein a predetermined threshold SNR value is used to determine a minimum confidence level that can be used to determine the match has been found.
20. The optical code scanner of claim 14 , wherein the plurality of quantized image data for the known items are stored in a database stored in a memory.
21. One or more non-transitory digital storage media storing data and instructions which, when the instructions are executed by one or more computing devices, cause performance of the method recited in claim 1 .