Hi everyone. I am trying to generate a small images 20x20 with white symbols on black backround and export them in binary format for training my Neural Net. I need a bunch of images which are rotated and scaled on different values. In total I have about 4000 images to export.

(More details: I binarize images and save a bunch of zeros and ones all in one file. I also have a description file which contains lines describing symbol and its transformation)

Here is a code I use and I have problems with it. It is slow and it leads to "not enough memory". I completely do not understand this memory issue, I have about 3.5Gb free for it.

I appriciate any help from anyone, thank you very much.

dim = 20;

digit[\[Alpha]_, s_, d_] := 
 Binarize[Graphics[
   Text[Style[ToString[d], Black, s {dim, dim}], {0., 0.}, 
    Center, {Cos[\[Alpha]/360. 2 \[Pi]], Sin[\[Alpha] 2 \[Pi]/360.]}],
    AspectRatio -> 1, ImageSize -> {dim, dim}], {0, 0.5}]

DescriptionString[symb_, w_, h_, deg_, scale_] := 
 symb <> "\t" <> ToString[w] <> "\t" <> ToString[h] <> "\t" <> 
  ToString[deg] <> "\t" <> ToString[scale]

SaveDataSet[dir_, symbols_, w_, h_, degrees_, scales_] := Module[
   {images, descriptions, ostreamDesc, ostreamImag},
   DeleteDirectory[dir, DeleteContents -> True];
   CreateDirectory[dir];
   ostreamDesc = OpenWrite[dir <> "/dict"];
   ostreamImag = OpenWrite[dir <> "/images.bin", BinaryFormat -> True];
   Do[
    With[{scale = Random[Real, {0.4, 1.0}]},
     With[{img = ImageData@digit[degree, scale, symb], 
       desc = DescriptionString[symb, w, h, degree, scale]},
      BinaryWrite[ostreamImag, img]; WriteLine[ostreamDesc, desc];]],
    {symb, symbols}, {degree, degrees}];
   Close[ostreamDesc];
   Close[ostreamImag];
   ];

(*THIS LEADS TO OUT OF MEMORY ISSUE*)
SaveDataSet["e:/work/HL/Digits/BinDigitsRnd", {"0", "1", "2", "3", 
  "4","5","6","7","8","9"}, dim, dim, Range[0.0, 360.0 - 0.00001, 1.0], {0.9}]