[SSTV] Added image converter tool

extras/SSTV_Image_Converter/.gitignore

@@ -0,0 +1,4 @@
+# ignore all output files
+*.h
+*.png
+!radiolib.png

extras/SSTV_Image_Converter/ImageConverter.py

@@ -0,0 +1,50 @@
+#!/usr/bin/python3
+# -*- encoding: utf-8 -*-
+
+import argparse
+import numpy as np
+from PIL import Image
+from argparse import RawTextHelpFormatter
+
+def main():
+  parser = argparse.ArgumentParser(formatter_class=RawTextHelpFormatter, description='''
+        RadioLib image to array conversion tool.
+
+        Input is a PNG image to be transmitted via RadioLib SSTV.
+        The image must have correct size for the chose SSTV mode!
+
+        Output is a file (by default named "img.h") which can be included and transmitted.
+        The resulting array will be very large (typically 320 kB),
+        make sure your platform has sufficient Flash/RAM space.
+    ''')
+  parser.add_argument('input',
+      type=str,
+      help='Input PNG file')
+  parser.add_argument('output',
+      type=str,
+      nargs='?',
+      default='img',
+      help='Output header file')
+  args = parser.parse_args()
+  outfile = f'{args.output}.h'
+  print(f'Converting "{args.input}" to "{outfile}"')
+
+  # open the image as numpy array
+  img = Image.open(args.input)
+  arr = np.array(img)
+
+  # open the output file
+  with open(outfile, 'w') as f:
+    print(f'const uint32_t img[{arr.shape[0]}][{arr.shape[1]}] = {{', file=f)
+    for row in arr:
+      print('  { ', end='', file=f)
+      for pix in row:
+        rgb = pix[0] << 16 | pix[1] << 8 | pix[2]
+        print(hex(rgb), end=', ', file=f)
+      print(' },', file=f)
+    print('};', file=f)
+  
+  print('Done!')
+
+if __name__ == "__main__":
+    main()