Possible means to speed up Bitmap TONE code?

[DerVVulfman]

Well, this is what I wanna speed up within RPGMaker XP...

Code:

#==============================================================================
# ** Bitmap
#------------------------------------------------------------------------------
#  The bitmap class. Bitmaps are expressions of so-called graphics.
#==============================================================================

class Bitmap
  #-------------------------------------------------------------------------
  # * Tone Adjust
  #    r : red adjustment   (defaulted to 0 middle of -255 - 255 range)
  #    g : green adjustment (defaulted to 0 middle of -255 - 255 range)
  #    b : blue adjustment  (defaulted to 0 middle of -255 - 255 range)
  #-------------------------------------------------------------------------
  def tone_adjust(r=0, g=0, b=0)

    # Adjust values to be within -255 to 255 ranges
    r   = tone_ranges(r)
    g   = tone_ranges(g)
    b   = tone_ranges(b)

    # Cycle through the bitmaps pixels
    for x in 0..self.width
      for y in 0..self.height
        #
        # Base mechanics for each pixel
        color = self.get_pixel(x, y)                  # Get single pixel color
        next  if color.alpha == 0                     # Skip if transparent
        rr    = color.red   + r                       # Adjust the red
        gg    = color.green + g                       # Adjust the green
        bb    = color.blue  + b                       # Adjust the blue
        self.set_pixel(x, y, Color.new(rr, gg, bb))   # Replace the pixel
        #
      end
    end

  end 
  #-------------------------------------------------------------------------
  # * Tone Range Adjustment
  #    value : value (forced to stay in -255 to -255 range)
  #-------------------------------------------------------------------------
  def tone_ranges(value)
    value = -255    if value < 255
    value =  255    if value > 255
  end
end

Now within RPGMaker XP:

• You can hue-adjust bitmaps within a 0-360 range.
  
• You can tone adjust sprites, or increase the red, green and/or blue tones in a range of -255 to 255, darkening or lightening them accordingly.
  

But, you'd think they woulda PUT TONE ADJUST INTO THE BITMAP CLASS?????

---

Still, for anything large, this code does take some time to change a bitmap.  If I could adjust the bitmap with the Tone class I could with sprites, it would be dang near instantaneous.  Unfortunately, I need something FAAAAST!

And no. You cannot tone adjust a sprite and copy the contents into a bitmap.  The sprite's own properties are what is adjusted, not the bitmap contained within.

So, does anyone know of a faster means to adjust the tone of a bitmap?