Hi @ikram.haq ,
Thanks for your help. I’m not sure the mechanism to determine the DPI value and have too much noise. I’m not sure my understanding is correct, but I think DPI can be seen as one kind of resolution (the DPI value depends on the paper size). If considering the paper size, I think the resolution of the picture is enough?
This is the original answer sheet in Aspose example, and the resolution of my photo is as same as this.
What I use it to use the mobile to take a photo on the OMR card.
Then, I use automatically perspective correction, crop and resize the picture.
Finally, I increase the color contrast, then feed it to the OMR engine.
The code I use is this one (https://docs.aspose.com/display/ocrnet/Extracting+and+Managing+OMR#ExtractingandManagingOMR-ExtractingOMR:SampleCode) with your suggestion adding the threshold level. Is there any better tool for the image preprocessing? I don’t see there is any image preprocessing in the sample code.
I’m not sure which step is incorrect since the OMR Engine can’t still correctly recognize my answer sheet.