Partial or entire Image Blurring in TikZ?
I have seen some examples of drop shadow blurring in the pgf-blur package version 1.01 by Martin Giese but this isn’t what I mean. Is it somehow possible to do partial or entire Image Blurring in TikZ, just like what one may do in Adobe Photoshop?
Maybe one could copy the original picture lets say 8 times, add a transparency of 50% and then shift the different copies randomly and then overlay everything.
I took his idea and made an example.
The logic in my example:
The Code:
\documentclass[tikz]{standalone}
%\usepackage{luatex85} %if used with lualatex
\usepackage{graphicx}
%Parameters:
%- at position
%- blur parameter
%- image name
\newcommand\blurredimage[3]{
\node[opacity=0.2] at (#1) {\includegraphics{#3}};
\node[opacity=0.2] at (#1+ #2, #2) {\includegraphics{#3}};
\node[opacity=0.2] at (#1+-#2, #2) {\includegraphics{#3}};
\node[opacity=0.2] at (#1+-#2,-#2) {\includegraphics{#3}};
\node[opacity=0.2] at (#1+ #2,-#2) {\includegraphics{#3}};
}
% ----------------------------------------------------------------
\begin{document}
\begin{tikzpicture}
\blurredimage{0.0,0.0}{.2}{mypic}
\begin{scope}
\clip (-3.5,-8) rectangle (-1,-5);
\node[] at (0,0) {\includegraphics{mypic}};
\end{scope}
\end{tikzpicture}
\end{document}
Taking an image from Wikipedia you get the following result:
To make it more flexible you could use key value parameters for blur factor, opacity (and position?).
Maybe you could get better results with a pattern over the background images.
To blur only areas you can do it in the opposite way: Insert the image, then add multiple times a clipped area of the image.
Image blurring is essentially a pixel-based operation and hence vector based diagrams need to be treated as rasterized images. TikZ or TeX cannot handle this on their own.
The image needs to be exported, blurred and then brought back and used as external image or some quite nontrivial hacks to save it to a box as a snapshot and somehow loose the vector graphics properties so on. I can't think of anyway to do that automatically now but some external function calls can be added just to blur the images after externalization.
Here's a sagetex solution, not using tikz for blurring the Wikipedia picture. Just find some Python code online, such as from here to find many ways of manipulating your image. I've picked BLUR and CONTOUR.
\documentclass{article}
\usepackage{sagetex}
\usepackage{graphicx}
\begin{document}
Here is the images:\\
\includegraphics[width=2in]{Mona.png}
\begin{sagesilent}
from PIL import Image
from PIL import ImageFilter
from PIL.ImageFilter import (BLUR,CONTOUR)
img = Image.open('Mona.png')
img.filter(BLUR).save('MonaBlur.png')
img.filter(CONTOUR).save('MonaContour.png')
result1 = r"\includegraphics[width=2in]{MonaBlur.png}"
result2 = r"\includegraphics[width=2in]{MonaContour.png}"
\end{sagesilent}
\sagestr{result1}
\sagestr{result2}
\end{document}
The result is shown below, running in CoCalc:
EDIT: Now to handle the partial blurring. From this page I get some instruction on cropping and pasting the cropped image onto another image. I cropped the hands from the original image and pasted them onto the blurred image of the blurred image.
\documentclass{article}
\usepackage{sagetex}
\usepackage{graphicx}
\begin{document}
Here is the images:\\
\includegraphics[width=2in]{Mona.png}
\begin{sagesilent}
from PIL import Image
from PIL import ImageFilter
from PIL.ImageFilter import (BLUR,CONTOUR)
img = Image.open('Mona.png')
Copyimg = img.copy()
croppedIm = img.crop((75, 340, 200, 450))
croppedIm.save('cropped.png')
Copyimg.paste(croppedIm, (0, 0))
img.filter(BLUR).save('MonaBlur.png')
img.filter(CONTOUR).save('MonaContour.png')
img2 = Image.open('MonaBlur.png')
img2.filter(BLUR).save('MonaBlurBlur.png')
img2.paste(croppedIm, (75, 340, 200, 450))
img2.paste(croppedIm, (400, 500))
img2.save('box.png')
result1 = r"\includegraphics[width=2in]{MonaBlur.png}"
result2 = r"\includegraphics[width=2in]{MonaContour.png}"
result3 = r"\includegraphics[width=2in]{box.png}"
result4 = r"\includegraphics[width=2in]{cropped.png}"
\end{sagesilent}
\sagestr{result1}
%\sagestr{result2}
\sagestr{result3}
\sagestr{result4}
\end{document}
The output in CoCalc is now:
The last image is the crop of the hands. This has been pasted onto the spot where it was taken from but now it's on the blurred image. If you click on the image (for a closer view) you will see that the second of the 3 pictures has a fuzzy Mona, except for her hands.
By using Python you get access to a lot of built in commands to manipulate your images.
tikzpicture, or are you wanting to blur parts drawn in TikZ? – Paul Gessler Feb 21 '16 at 14:26