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An automatic data collection device (10) and method reads images from display screen (22) of an electronic display device (24), such as a cellular telephone. The method reads a flashing image of a target machine-readable symbol (12) displayed on the display screen, by obtaining at least two images o

An automatic data collection device (10) and method reads images from display screen (22) of an electronic display device (24), such as a cellular telephone. The method reads a flashing image of a target machine-readable symbol (12) displayed on the display screen, by obtaining at least two images of the display screen. In the first image, the image of the target machine-readable symbol is present. In the second image, the image of the target machine-readable symbol (12) is absent. The second image of the display screen, when the image of the target machine-readable symbol is absent, comprises noise and other images that are irrelevant to the decoding process. This noise in the second image is subtracted from the first image of the display screen having the image of the target machine-readable symbol displayed thereon the symbol. A resulting image from the image subtraction is an improved image of the target machine-readable symbol.

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1. A method usable with an imager type automatic data collection device, the method comprising: obtaining a first image of a display screen of an electronic display device, the first image including noise and an image of a target machine-readable symbol that is affected by the noise;obtaining a seco

1. A method usable with an imager type automatic data collection device, the method comprising: obtaining a first image of a display screen of an electronic display device, the first image including noise and an image of a target machine-readable symbol that is affected by the noise;obtaining a second image of the display screen, the second image having the image of the target machine-readable symbol absent therefrom and including the noise; andsubtracting the second image from the first image to substantially remove the noise and to obtain a third image that includes a resulting improved image of the target machine-readable symbol. 2. The method of claim 1 wherein obtaining the first and second images of the display screen of the electronic display device includes obtaining the first and second images of the display screen of a wireless electronic display device. 3. The method of claim 1 wherein obtaining the first and second images of the display screen of the electronic display device includes obtaining the first and second images of the display screen of a wired electronic display device. 4. The method of claim 1 wherein subtracting the second image from the first image includes performing a pixel-to-pixel subtraction of corresponding pixel values between the first and second images. 5. The method of claim 4 wherein performing pixel-to-pixel subtraction includes: obtaining corresponding output pixel values from the pixel-to-pixel subtraction; andobtaining absolute pixel values from the output pixel values. 6. The method of claim 4 wherein performing pixel-to-pixel subtraction includes: obtaining corresponding signed output pixel values from the pixel-to-pixel subtraction; andtransforming the signed output pixel values to pixel values that can be presented in the resulting improved image. 7. The method of claim 1 wherein obtaining the first and second images that include the noise comprises obtaining images that are affected by one or more of a lighting problem, a reflection, a scratch on the display screen, a microstructure of the display screen, text presented on the display screen, and image portions that are irrelevant to a decoding of the target machine-readable symbol. 8. The method of claim 1, further comprising adjusting either or both the first and second images prior to subtracting. 9. The method of claim 8 wherein adjusting includes aligning the second image relative to the first image. 10. The method of claim 1 wherein obtaining the second image includes timing acquisition of the second image in between intermittent presentation of the image of the target machine-readable symbol in the display screen. 11. The method of claim 1 wherein obtaining the first image that includes the image of the target machine-readable symbol includes acquiring an image of a matrix code symbol. 12. An automatic data collection apparatus usable to read a target machine-readable symbol, the apparatus including: a sensor adapted to obtain a first image of a display screen of an electronic display device, the first image including a first image portion having an image of the target machine-readable symbol and having noise, the sensor further being adapted to obtain a second image of the display screen, the second image including a second image portion having the noise, the image of the target machine-readable medium being absent from the second image;a memory coupled to the sensor to store the obtained first and second images that respectively include the first and second image portions; anda processor coupled to the memory to obtain a difference between the stored first and second image portions, the difference representing the image of the target machine-readable symbol at least partially devoid of the noise. 13. The apparatus of claim 12 wherein the processor is further coupled to the memory to perform an adjustment of either or both of the stored first and second images, including adjustment of an alignment between the first and second images. 14. The apparatus of claim 12 wherein the processor is coupled to the memory to obtain the difference by subtracting pixel values of one of the stored images from corresponding pixel values of an other of the stored images. 15. The apparatus of claim 12 wherein the processor is adapted to control timing of the sensor to obtain the second image in between intermittent presentation of the first image, having the image of the target machine-readable symbol, by the display screen. 16. The apparatus of claim 15 wherein the timing of the sensor is at least equal to or greater than a rate of intermittent presentation of the first image by the display screen. 17. The apparatus of claim 15 wherein the processor is adapted to control timing of the sensor to obtain the second image in response to manual user activation. 18. An automatic data collection system usable to read a target machine-readable symbol, the apparatus including: sensor means for acquiring a first image that includes a first image portion having an image of the target machine-readable symbol and having noise, the sensor means further being adapted for acquiring a second image that includes a second image portion having the noise, the image of the target machine-readable medium being absent from the second image; andmeans for obtaining a difference between the first and second image portions, the difference representing the image of the target machine-readable symbol at least partially devoid of the noise. 19. The system of claim 18 wherein the means for obtaining the difference includes subtraction means for subtracting pixel values associated with the second image from corresponding pixel values associated with the first image, the system further including means for using output pixel values that result from the subtraction by the subtracting means to generate the image of the target machine-readable symbol that is at least partially devoid of the noise. 20. The system of claim 18, further comprising adjustment means for adjusting either or both the first and second images, including aligning the first and second image portions relative to each other. 21. The system of claim 18, further comprising: an electronic display device means for obtaining the image of the target machine-readable symbol to be acquired by said sensor means; anda display means associated with the electronic display device means for intermittently presenting the obtained image of the target machine-readable symbol in a manner that the presented image can be acquired by the sensor means. 22. The system of claim 18, further comprising: decoding means for decoding the image of the target machine-readable symbol that is at least partially devoid of the noise; andadditional means for supporting operation of the decoding means and sensor means. 23. An article of manufacture for an imager type automatic data collection device, the article of manufacture comprising: a storage medium having instructions stored thereon that are executable by a processor of said automatic data collection device to read a target machine-readable symbol, by:obtaining a first image of a display screen of an electronic display device, the first image including an image of the target machine-readable symbol and image portions that are irrelevant to decoding of the target machine-readable symbol;obtaining a second image of the display screen that includes the image portions that are irrelevant to the decoding of the target machine-readable symbol, the image of the target machine-readable symbol being absent from the second image; andobtaining a difference between the first and second images to substantially remove the image portions and to yield the image of the target machine-readable symbol. 24. The article of manufacture of claim 23 wherein the instructions to obtain the difference between the first and second images include instructions executable by said processor to read said target machine-readable symbol, by: subtracting the second image from the first image. 25. The article of manufacture of claim 24 wherein the instructions to subtract the second image from the first image include instructions executable by said processor to read said target machine-readable symbol, by: subtracting pixel values associated with the second image from corresponding pixel values associated with the first image. 26. The article of manufacture of claim 23 wherein the storage medium further includes instructions stored thereon that are executable by the processor to read the target machine-readable symbol, by: aligning the obtained first and second images relative to each other; andperforming other adjustments to either or both the obtained first and second images to facilitate their alignment. 27. The article of manufacture of claim 23 wherein the instructions to obtain the first image that includes the image of the target machine-readable symbol include instructions executable by said processor to read said target machine-readable symbol, by: obtaining a magnified image of the target machine-readable symbol to distinguish geometric elements of the target machine-readable symbol from microstructures of the display screen. 28. The article of manufacture of claim 23 wherein the instructions to obtain the second image of the display screen that includes the image portions that are irrelevant to the decoding of the target machine-readable symbol include instructions executable by said processor to read said target machine-readable symbol, by: obtaining the second image having noise that distorts the image of the target machine-readable symbol. 29. The article of manufacture of claim 23 wherein the instructions to obtain the second image of the display screen that includes the image portions that are irrelevant to the decoding of the target machine-readable symbol include instructions executable by said processor to read said target machine-readable symbol, by: obtaining the second image having image portions that lie outside of the image of the target machine-readable symbol. 30. The article of manufacture of claim 23 wherein the storage medium further includes instructions stored thereon that are executable by the processor to read the target machine-readable symbol, by: repeating the obtaining of at least the second image; andusing at least some values derived from the repeatedly obtained second image to further remove irrelevant image portions from the yielded image of the target machine-readable symbol.