Change image color in PIL module

Question

I am trying to vary the intensity of colors to obtain a different colored image...

import PIL
from PIL import Image
from PIL import ImageEnhance
from PIL import ImageDraw

# read image and convert to RGB
image=Image.open("readonly/msi_recruitment.gif")
image=image.convert('RGB')

# build a list of 9 images which have different brightnesses
enhancer=ImageEnhance.Brightness(image)
images=[]
for i in range(1, 10):
    images.append(enhancer.enhance(i/10))

# create a contact sheet from different brightnesses
first_image=images[0]
contact_sheet=PIL.Image.new(first_image.mode, (first_image.width*3,first_image.height*3))
x=0
y=0

for img in images:
    # Lets paste the current image into the contact sheet
    contact_sheet.paste(img, (x, y) )
    # Now we update our X position. If it is going to be the width of the image, then we set it to 0
    # and update Y as well to point to the next "line" of the contact sheet.
    if x+first_image.width == contact_sheet.width:
        x=0
        y=y+first_image.height
    else:
        x=x+first_image.width

# resize and display the contact sheet
contact_sheet = contact_sheet.resize((int(contact_sheet.width/2),int(contact_sheet.height/2) ))
display(contact_sheet)

But the above code just varies brightness.... Please tell me what changes should i make to vary color intensity in this code..... Im sorry but i am unable to upload the picture now, consider any image you find suitable and help me out... Appreciated!!!!

Please go to this link and answer this question instead of this one, I apologise for inconvenience....

Pixel colour intensity

Answer 1

Many colour operations are best done in a colourspace such as HSV which you can get in PIL with:

HSV = rgb.convert('HSV')

You can then use split() to get 3 separate channels:

H, S, V = hsv.split()

Now you can change your colours. You seem a little woolly on what you want. If you want to change the intensity of the colours, i.e. make them less saturated and less vivid decrease the S (Saturation). If you want to change the reds to purples, i.e. change the Hues, then add something to the Hue channel. If you want to make the image brighter or darker, change the Value (V) channel.

When you have finished, merge merge((H,S,V)) the edited channels back together and convert back to RGB with convert('RGB').

See Splitting and Merging and Processing Individual Bands on this page.

---

Here is an example, using this image:

Here is the basic framework to load the image, convert to HSV colourspace, split the channels, do some processing, recombine the channels and revert to RGB colourspace and save the result.

#!/usr/bin/env python3

from PIL import Image

# Load image and create HSV version
im = Image.open('colorwheel.jpg')
HSV= im.convert('HSV')

# Split into separate channels
H, S, V = HSV.split()

######################################
########## PROCESSING HERE ###########
######################################

# Recombine processed H, S and V back into a recombined image
HSVr = Image.merge('HSV', (H,S,V))
# Convert recombined HSV back to reconstituted RGB
RGBr = HSVr.convert('RGB')

# Save processed result
RGBr.save('result.png')

So, if you find the chunk labelled "PROCESSING HERE" and put code in there to divide the saturation by 2, it will make the colours less vivid:

# Desaturate the colours by halving the saturation
S = S.point(lambda p: p//2) 

If, instead, we halve the brightness (V), like this:

# Halve the brightness
V=V.point(lambda p: p//2) 

the result will be darker:

If, instead, we add 80 to the Hue, all the colours will rotate around the circle - this is called a "Hue rotation":

# Rotate Hues around the Hue circle by 80 on a range of 0..255, so around 1/3 or a circle, i.e. 120 degrees:
H = H.point(lambda p: p+80) 

which gives this: