Image recognition for Android - test score exam app with very high precision

I need an Android app. I already have a design for it, I just need it to be built. Image recognition app for Android for school exam testing In our school we use exam tests with 40 bullets for answers as per enclosed jpg file. So there are 2 x 20 lines. Each line has 4 empty bullets, and the student will either fill one bullet per line (or none at all for a given line). Student may use colors black, grey, blue, red, grey-shade pencil to fill out the empty dots. . The empty dots may be partially or fully filled out and may fill a little bit outside the areas of the empty dots. There is only one answer per line of the 2 x 20 lines. If app identifies 2 answers on a given line, then it should only identify the dot that has the largest filled area. When taking pictures, then sometimes part of the white paper may become grey-ish. App should still be able to identify correct dots filled out. App must fill out correctly 100% correctly all the enclosed sample images enclosed. Data flow: 1) When user starts app then user writes an identifier up to 5 characters. 2) Then user sees a screen with A, B, C, D for empty dots as 2 x 20 lines. User clicks on either A, B, C, D on each line and repeats that until all 40 lines have at least 1 answer. 3) User clicks "save project". Thats it. 1) To calculate exam scores user opens app and can then select between a list of up to 100 saved projects. 2) then app opens camera and user then clicks every time user wants app to take a picture OR can choose "Auto" so app automatically takes snapshot when picture is clear and it shows for each line with a red or blue circle, for identified filled out bullets. App then also calculate and show on screen these numbers: 1) identified lines 2) un-identified lines 3) Correct answers/ score (1 point per answer) 4) in-correct answers (No score) 3) By clicking on the screen then app immediately start for the next exam paper to image and score