Python Doesnt Clear Rendermap / RGB Tint Map

[victorEFVH7]

I have some issues with rendermap and python. For some reason it doesnt want to clear the bitmaps.

The issue is that it looks like the bitmap / rgbtint doesnt want to clear in python and it stores the image somehow even though it has been overwritten on disk. So when I use the rendermap it just rerenders the previous image.

Process (I would like to avoid PIL or any non native library if possible).

1. I save a multimatte from vray framebuffer using python. 

2. I open the image as a rgbtint and convert the red channel to a black and white mask and the overide save as the multimatte. 

3. When I run the script again it will use the first image that has been exported in the current max session and it drives me nuts because its not a problem in regular maxscript.

Python

        mapbm = rt.bitmaptexture()
        mapbm.bitmap = rt.openbitmap('C:/Multimatte.jpg', gamma=2.2)
        # Create a RGB Tint to convert RGB to BW
        rgbtintmap = rt.rgbtint()
        rgbtintmap.red = rt.color(255, 255, 255)
        rgbtintmap.green = rt.color(0, 0, 0)
        rgbtintmap.blue = rt.color(0, 0, 0)
        rgbtintmap.map1 = mapbm

        # Create a new temporary bitmap
        tmptexbitmap = rt.bitmap(mapbm.bitmap.width, mapbm.bitmap.height)
        tmptexbitmap.filename = 'C:/Multimatte.jpg'

        # Render the image into the temporary bitmap
        rt.rendermap(rgbtintmap, into=tmptexbitmap, filter=True)
        rt.save(tmptexbitmap, gamma=2.2)

        # Close the temporary bitmap
        rt.close(tmptexbitmap)

        # Close the original bitmap
        rt.close(mapbm.bitmap)

Maxscript version which works as it should.

(
	local mapbm = bitmaptexture()
	mapbm.bitmap = openbitmap @"C:\Multimatte.jpg" 
	local rgbtintmap = rgbtint()
	rgbtintmap.red = color 255 255 255
	rgbtintmap.green = color 0 0 0
	rgbtintmap.blue = color 0 0 0
	rgbtintmap.map1 = mapbm
	local tmptexbitmap = bitmap mapbm.bitmap.width mapbm.bitmap.height
	tmptexbitmap.filename = @"C:\Multimatte.jpg"
	rendermap rgbtintmap into:tmptexbitmap 
	save tmptexbitmap gamma:2.2

	close (tmptexbitmap)
	free tmptexbitmap 
	free mapbm
	free rgbtintmap
)