function getImageData8bits(imageData, indexes, colormap, width, y_start, y_step, y_end, x_start, x_step, x_end)
   {
      var color, i, x, y;

      for (i = 0, y = y_start; y !== y_end; y += y_step) {
         for (x = x_start; x !== x_end; x += x_step, i++) {
            color = indexes[i];
            imageData[(x + width * y) * 4 + 3] = 255;
            imageData[(x + width * y) * 4 + 2] = colormap[(color * 3) + 0];
            imageData[(x + width * y) * 4 + 1] = colormap[(color * 3) + 1];
            imageData[(x + width * y) * 4 + 0] = colormap[(color * 3) + 2];
         }
      }

      return imageData;
   }
Return a ImageData object from a TGA file (8bits)

@param {Array} imageData - ImageData to bind
@param {Array} indexes - index to colormap
@param {Array} colormap
@param {number} width
@param {number} y_start - start at y pixel.
@param {number} x_start - start at x pixel.
@param {number} y_step  - increment y pixel each time.
@param {number} y_end   - stop at pixel y.
@param {number} x_step  - increment x pixel each time.
@param {number} x_end   - stop at pixel x.
@returns {Array} imageData