Question

Python3

Write a program to apply a 'negative' filter on a greyscale image. The program should ask the user to enter a filename, open this file, perform the transformation (as described below) and then save the negative version of the image to the file 'output.png'.

To perform the negative effect, set each pixel in the output image to the opposite colour value than the corresponding pixel in the input image. For example, a colour value of 0 would become 255, 1 would become 254, 253 would become 2, and so on.

Here is an example of the effect your program should produce: astronaut.png Enter a filename: astronaut.png output.png

Answer 1

def displayImageFileOnLCD(filename):
print 'displays ', filename
title = 'Review Mode'
# resize/dither to screen resolution and send to LCD
image = Image.open(filename)
im_width, im_height = image.size
if im_width < im_height:
image = image.rotate(90)
image.thumbnail(S_SIZE, Image.ANTIALIAS)
image_sized = Image.new('RGB', S_SIZE, (0, 0, 0))
image_sized.paste(image,((S_SIZE[0] - image.size[0]) / 2, (S_SIZE[1] - image.size[1]) / 2))
# draw filename
draw = ImageDraw.Draw(image_sized)
font = ImageFont.truetype('arial.ttf', 18)
draw.rectangle([(0, 0), (115, 22)], fill=(255,255,255), outline=(0,0,0))
draw.text((2, 2), title, fill='black', font=font)
draw.rectangle([(279, 217), (399, 239)], fill=(255,255,255), outline=(0,0,0))
draw.text((290, 218), filename, fill='black', font=font)
# display on LCD
image_sized = ImageOps.invert(image_sized)
image_sized = image_sized.convert('1') # convert image to black and white
lcd.write(image_sized.tobytes())