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recreating early ai experiments - character recognition

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Recreating one of the early ai experiments : recognising handwritten numbers


The MNIST dataset features some 60,000 handwritten characters (digits), captured in 28x28 pixel frames


In this experiment only the first 200 of these 60,000 digits are used

Training based on this small trainingset only takes about 30 seconds


The testset contains some 20 digits randomly taken from the dataset

These digits have not been used in the training


Given these constraints it all performs amazingly well


Give it more trainingdata and increase training time and it only becomes better








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The images are in a 28x28 matrix

this translates to a neural network of 28*28=784 input neurons (1 for each pixel), 100 or so hidden neurons and 10 output neurons (digits 0-9)


so each picture translates to an input format of "array[784] of float", filled with rgb values i.e. [0,0,0,0,255,143, ... 0,0,0]


and a target output format of "array[10] of float" i.e. [0.01, 0.01, 0.99, 0.01 .... 0.01] where the output value in this example denotes a '2'


note :

although rgb values are integers, I used floats in the input format as all rgb values are recalculated to a value between 0.01 and 0.99


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