Merging background with transparent image in PIL
I have a png image as background and I want to add a transparent mesh to this background but this doesn't work as expected. The background image is converted to transparent on places where I apply transparent mesh.
I am doing:
from PIL import Image, ImageDraw
map_background = Image.open(MAP_BACKGROUND_FILE).convert('RGBA')
map_mesh = Image.new('RGBA', (width, height), (0, 0, 0, 0))
draw = ImageDraw.Draw(map_mesh)
# Create mesh using: draw.line([...], fill=(255, 255, 255, 50), width=1)
...
map_background.paste(map_mesh, (0, 0), map_mesh)
But the result is:
You can see a chessboard pattern if you look carefully (used in graphics programs as no background). Transparent lines makes the background layer transparent too in places where both layers met. But I only want the transparent line to be added on top of the background.
I can solve it with:
map_background.paste((255,255,255), (0, 0), map_mesh)
but as I use different colors for different lines, I would have to make for every color this process. If I had 100 colors, then I need 100 layers what is not very good solution.
Asked by: John177 | Posted: 30-11-2021
Answer 1
What you are trying to do is to composite the grid onto the background, and for that you need to use Image.blend or Image.composite. Here's an example using the latter to composite red lines with random alpha values onto a white background:
import Image, ImageDraw, random
background = Image.new('RGB', (100, 100), (255, 255, 255))
foreground = Image.new('RGB', (100, 100), (255, 0, 0))
mask = Image.new('L', (100, 100), 0)
draw = ImageDraw.Draw(mask)
for i in range(5, 100, 10):
draw.line((i, 0, i, 100), fill=random.randrange(256))
draw.line((0, i, 100, i), fill=random.randrange(256))
result = Image.composite(background, foreground, mask)
From left to right:
[background] [mask]
[foreground]
[result]
(If you are happy to write the result back to the background image, then you can use one of the masked versions of Image.paste, as pointed out by Paulo Scardine in a deleted answer.)
Answer 2
I had trouble getting the above examples to work well. Instead, this worked for me:
import numpy as np
import Image
import ImageDraw
def add_craters(image, craterization=20.0, width=256, height=256):
foreground = Image.new('RGBA', (width, height), (0, 0, 0, 0))
draw = ImageDraw.Draw(foreground)
for c in range(0, craterization):
x = np.random.randint(10, width-10)
y = np.random.randint(10, height-10)
radius = np.random.randint(2, 10)
dark_color = (0, 0, 0, 128)
draw.ellipse((x-radius, y-radius, x+radius, y+radius), fill=dark_color)
image_new = Image.composite(foreground, image, foreground)
return image_new
Similar questions
python - Merging a transparent image to another background
I have 2 images as below, both are in RGBA format
I want to overlay the object into a fixed region in the background. However, my co...
python - How to make a surface with a transparent background in pygame
Can someone give me some example code that creates a surface with a transparent background in pygame?
django - python PIL - background displayed opaque instead of transparent
I want to generate 32x32 sized thumbnails from uploaded images (actually avatars).
To prevent a thumbnail from being smaller than that size, I want to create a transparent 32x32 background and paste the thumbnail on it.
The code below tries to do so. However, the avatar is displayed on a black and opaque background; I lose transparency information somewhere through the process. Where am I doing wrong?...
How do I create a Status Icon / System Tray Icon with custom text and transparent background using Python and GTK?
Here is the code that I have so far to define the icon:
icon_bg = gtk.gdk.pixbuf_new_from_file('gmail.png')
w, h = icon_bg.get_width(), icon_bg.get_height()
cmap = gtk.gdk.Colormap(gtk.gdk.visual_get_system(), False)
drawable = gtk.gdk.Pixmap(None, w, h, 24)
drawable.set_colormap = cmap
gc = drawable.new_gc()
drawable.draw_pixbuf(gc, icon_bg, 0, 0, 0, 0, w, h)
drawn_icon = gtk.gdk.Pixbuf(gtk.gdk.COLORSPAC...
python - How to get transparent background in window with PyGTK and PyCairo?
I've been trying really hard to create a window with no decoration and a transparent background using PyGTK. I would then draw the content of the window with Cairo. But I can't get it to work.
I've tried a lot of different ways, they all failed, this is one of them
#!/usr/bin/env python
import pygtk
pygtk.require('2.0')
import gtk, sys, cairo
win = None
def expose (widget, event):
cr = widget...
White background to transparent background using PIL python
How can i transform all white background and white elements of a png or jpg image in a transparent backgroun using PIL?
java - Detect if .swf has transparent background
Is there a way to do this programmatically in PHP, Python or Java?
Use case:
User uploads .swf through an upload form.
Detect if it has a transparent background.
If it does, change it to something else, e.g. white.
user interface - I want to make a transparent BACKGROUND frame with my python app (WxPython)
I've always wanted to make a app that's transparent, I love how it looks. I tried to make on of my apps transparent with the SetTransparent(alpha), but I bumped into a big problem.
Yes it makes my app transparent (^。^), but it makes EVERYTHING transparent (=。=).
I have no idea how to fix this problem. Hours of research didn't really help out.
What I meant by background is, nothing el...
python - Transparent background file download from S3
I am trying to permit a python app to access various locations in a many-GB file stored in S3. I'd like to create a drop-in replacement file-like object that intelligently downloads chunks of data from S3 in a separate thread to meet seek() and read() requests.
Is there a simple data structure I can use to store arbitrary intervals of the file?
It must support O(log n) look-up and O(n) insertion (n=number o...
c++ - How to make wxPython, DC background transparent?
How can i make the default white DC background become invisible (transparent)?
Run the following example, it shows a white background over a button. I would like to remove the white background of the DC. (to show only the red X)
import wx
class drawover(wx.Window):
def __init__(self, parent):
wx.Window.__init__(self, parent)
self.Bind(wx.EVT_PAINT, self.OnPaint)
self....
python - Transparent background in gnuplot multiplot
I'd like to get a transparent background in my gnuplot figure.
What I coded till now is:
#! /usr/bin/python
from numpy import *
import Gnuplot as gp
import Gnuplot.funcutils
x = (1,2,3)
y=(2,4,5)
x1 = (3,6,8)
g = gp.Gnuplot()
g("set terminal svg size 200,400")
g("set output 'filename.svg'")
g("unset xtics")
g("unset ytics")
g("set multiplot layout 3,1 title 'Title here'")
g("set object 1 rectangle from ...
python - How to make a surface with a transparent background in pygame
Can someone give me some example code that creates a surface with a transparent background in pygame?
python - How to use PIL to make all white pixels transparent?
I'm trying to make all white pixels transparent using the Python Image Library. (I'm a C hacker trying to learn python so be gentle)
I've got the conversion working (at least the pixel values look correct) but I can't figure out how to convert the list into a buffer to re-create the image. Here's the code
img = Image.open('img.png')
imga = img.convert("RGBA")
datas = imga.getdata()
newData = list()
for i...
pygame - Updating part of a surface in python, or transparent surfaces
I have an application written in python that's basically an etch-a-sketch, you move pixels around with WASD and arrow keys and it leaves a trail. However, I want to add a counter for the amount of pixels on the screen. How do I have the counter update without updating the entire surface and pwning the pixel drawings?
Alternatively, can I make a surface that's completely transparent except for the text so you can se...
django - python PIL - background displayed opaque instead of transparent
I want to generate 32x32 sized thumbnails from uploaded images (actually avatars).
To prevent a thumbnail from being smaller than that size, I want to create a transparent 32x32 background and paste the thumbnail on it.
The code below tries to do so. However, the avatar is displayed on a black and opaque background; I lose transparency information somewhere through the process. Where am I doing wrong?...
python - Transparent FrameBuffer background in OpenGL
I want to use glClear and glClearColor to fill a frame buffer with a colour including alpha transparency. However the framebuffer always renders as opaque when binded to a texture which is rendered to the screen.
I want everything which is rendered to the framebuffer to kept their transparency. I just want to change the background.
See the following code:
def create_texture(surface):
surface...
How do I create a Status Icon / System Tray Icon with custom text and transparent background using Python and GTK?
Here is the code that I have so far to define the icon:
icon_bg = gtk.gdk.pixbuf_new_from_file('gmail.png')
w, h = icon_bg.get_width(), icon_bg.get_height()
cmap = gtk.gdk.Colormap(gtk.gdk.visual_get_system(), False)
drawable = gtk.gdk.Pixmap(None, w, h, 24)
drawable.set_colormap = cmap
gc = drawable.new_gc()
drawable.draw_pixbuf(gc, icon_bg, 0, 0, 0, 0, w, h)
drawn_icon = gtk.gdk.Pixbuf(gtk.gdk.COLORSPAC...
python - How to make cStringIO transparent to another function that expects a real local file
I came up with the following problem: CODE A works right now.. I am saving a png file called chart.png locally, and then I am loading it into the proprietary function (which I do not have access).
However, in CODE B, am trying to use cStringIO.StringIO() so that I do not have to write the file "chart.png" to the disk. But I cannot find a way to pass it to the pproprietaryfunction because it is expecting a real fil...
python - PIL: How to make area transparent in PNG?
I've been using PIL to crop Images, now I also want to make certain rectangular areas transparent, say
from PIL import Image
im = Image.open("sample.png")
transparent_area = (50,80,100,200)
...
python - Matplotlib transparent line plots
I am plotting two similar trajectories in matplotlib and I'd like to plot each of the lines with partial transparency so that the red (plotted second) doesn't obscure the blue.
EDIT: Here's the image with transparent lines.
python - Transparent 3D bar graphs
I would like to generate 3D bar graphs with transparent surfaces so that I can see what is going on behind tall bars.
The mplot3d API docs say that keywords are allowed for the bar3d function. I pass all the required parameters but can only output graphs with solid surfaces.
Still can't find your answer? Check out these communities...
PySlackers | Full Stack Python | NHS Python | Pythonist Cafe | Hacker Earth | Discord Python