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<!DOCTYPE html>
<html lang="en">
<head>
<!-- 2022-07-23 Sat 05:11 -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Scan notes with laptop webcam</title>
<meta name="generator" content="Org mode">
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<p>
<a href="index.html">Ivanaf</a>
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<p>
</p><h1>
Scan notes with laptop webcam
</h1><p>
</p>
<p>
<span class=page-date> <small>
2018-09-16, updated 2020-07-26 — <a href='journal.html#tech' class='tech tagbutton'>tech</a> <a href='journal.html#blog' class='blog tagbutton'>blog</a>   <a href="solving_a_problem_set_with_orgmode.html">⇦Solving a problem set with orgmode</a> – <a href="export_subtree_with_files.html">Export subtree with files⇨</a>
</small> </span>
</p>
<nav id="table-of-contents">
<input id="toggle-toc" style="display: none; visibility: hidden;" type="checkbox">
<label for="toggle-toc">
<h2> <b> Table of Contents </b> </h2>
</label>
<div id="text-table-of-contents">
<ul>
<li><a href="#controlling_the_brightness">1. Controlling the brightness</a></li>
<li><a href="#taking_the_picture">2. Taking the picture</a></li>
<li><a href="#cropping_the_picture">3. Cropping the picture</a></li>
<li><a href="#cleaning_the_image">4. Cleaning the image</a></li>
<li><a href="#putting_it_all_together">5. Putting it all together</a></li>
<li><a href="#results">6. Results:</a></li>
</ul>
</div>
</nav>
<p>
I was solving a pset, and realized that I needed to draw a graph by hand and include it in my solution. I didn't want to deal with taking a picture with my phone and sending the picture to my computer in order to use it. I wanted to be able to quickly scan it using my webcam.
</p>
<p>
So I decided to write a scrip to just do that, I press Ctrl-Print and the magic happens!
</p>
<p>
It sets my screen brightness to max. Takes a pic with my webcam. Sets the screen brightness to where it was. Prompts me to crop the picture it took. Uses <a href="http://www.fmwconcepts.com/imagemagick/textcleaner/index.php">textcleaner</a> to clean the picture up. And at last, it automatically inserts the picture in my org document, and displays the picture.
</p>
<p>
In other words, a quick and dirty scanner with computer screen flash to scan papers.
</p>
<div id="outline-container-controlling_the_brightness" class="outline-2">
<h2 id="controlling_the_brightness"><span class="section-number-2">1</span> Controlling the brightness</h2>
<div class="outline-text-2" id="text-1">
<p>
First I needed to allow me to control the brightness without sudo. Here I added my group as a group with permissions to edit the brightness.
</p>
<div class="org-src-container">
<pre class="src src-sh">sudo chgrp ivanaf /sys/class/backlight/intel_backlight/brightness
sudo /bin/chmod g+w /sys/class/backlight/intel_backlight/brightness
</pre>
</div>
<p>
Then I could just use
</p>
<div class="org-src-container">
<pre class="src src-sh"><span class="org-builtin">echo</span> brightness /sys/class/backlight/intel_backlight/brightness
</pre>
</div>
</div>
</div>
<div id="outline-container-taking_the_picture" class="outline-2">
<h2 id="taking_the_picture"><span class="section-number-2">2</span> Taking the picture</h2>
<div class="outline-text-2" id="text-2">
<p>
I use pygame to take the picture.
</p>
<div class="org-src-container">
<pre class="src src-python"><span class="org-keyword">import</span> pygame
<span class="org-keyword">import</span> pygame.camera
<span class="org-keyword">from</span> pygame.<span class="org-builtin">locals</span> <span class="org-keyword">import</span> *
<span class="org-keyword">import</span> sys
<span class="org-keyword">from</span> PIL <span class="org-keyword">import</span> Image
<span class="org-keyword">import</span> os
<span class="org-keyword">from</span> time <span class="org-keyword">import</span> time
<span class="org-keyword">import</span> numpy <span class="org-keyword">as</span> np
<span class="org-variable-name">DEVICE</span> = <span class="org-string">"/dev/video1"</span>
<span class="org-variable-name">SIZE</span> = (1280, 720)
<span class="org-comment-delimiter">#</span><span class="org-comment">https://www.pyimagesearch.com/2015/09/07/blur-detection-with-opencv/</span>
<span class="org-comment-delimiter">#</span><span class="org-comment">try:</span>
<span class="org-keyword">if</span> <span class="org-constant">True</span>:
<span class="org-keyword">import</span> cv2
<span class="org-variable-name">has_cv</span> = <span class="org-constant">True</span>
<span class="org-keyword">def</span> <span class="org-function-name">variance_of_laplacian</span>(image):
<span class="org-comment-delimiter"># </span><span class="org-comment">compute the Laplacian of the image and then return the focus</span>
<span class="org-comment-delimiter"># </span><span class="org-comment">measure, which is simply the variance of the Laplacian</span>
<span class="org-variable-name">ans</span> = cv2.Laplacian(image, cv2.CV_64F).var()
<span class="org-keyword">print</span>(ans)
<span class="org-keyword">return</span> cv2.Laplacian(image, cv2.CV_64F).var()
<span class="org-keyword">def</span> <span class="org-function-name">choose_best</span>(image1, image2):
<span class="org-keyword">if</span> variance_of_laplacian(pygame_to_cvimage(image1))>variance_of_laplacian(pygame_to_cvimage(image2)):
<span class="org-keyword">return</span> image1
<span class="org-keyword">return</span> image2
<span class="org-comment-delimiter">#</span><span class="org-comment">https://gist.github.com/jpanganiban/3844261</span>
<span class="org-keyword">def</span> <span class="org-function-name">pygame_to_cvimage</span>(surface):
<span class="org-doc">"""Convert a pygame surface into a cv image"""</span>
<span class="org-comment-delimiter">## </span><span class="org-comment">convert to pillow</span>
<span class="org-variable-name">pil_string_image</span> = pygame.image.tostring(surface, <span class="org-string">"RGB"</span>, <span class="org-constant">False</span>)
<span class="org-variable-name">pil_im</span> = Image.frombytes(<span class="org-string">"RGB"</span>, SIZE, pil_string_image)
<span class="org-variable-name">numpy_image</span> = np.array(pil_im)
<span class="org-variable-name">opencv_image</span> = cv2.cvtColor(numpy_image, cv2.COLOR_RGB2BGR)
<span class="org-variable-name">gray</span> = cv2.cvtColor(opencv_image, cv2.COLOR_BGR2GRAY)
<span class="org-keyword">return</span> gray
<span class="org-comment-delimiter">#</span><span class="org-comment">except ImportError:</span>
<span class="org-keyword">else</span>:
<span class="org-variable-name">has_cv</span> = <span class="org-constant">False</span>
<span class="org-keyword">def</span> <span class="org-function-name">choose_best</span>(image1, image2):
<span class="org-keyword">return</span> image2
<span class="org-comment-delimiter">#</span><span class="org-comment">based on https://gist.github.com/snim2/255151</span>
<span class="org-comment-delimiter">#</span><span class="org-comment">and https://www.pygame.org/docs/tut/CameraIntro.html</span>
<span class="org-keyword">if</span> <span class="org-builtin">__name__</span> == <span class="org-string">"__main__"</span>:
<span class="org-variable-name">file_name</span> = <span class="org-builtin">str</span>(sys.argv[1])
pygame.init()
pygame.camera.init()
<span class="org-variable-name">cam</span> = pygame.camera.Camera(DEVICE, SIZE)
cam.start()
<span class="org-variable-name">display</span> = pygame.display.set_mode(SIZE, 0)
<span class="org-variable-name">screen</span> = pygame.surface.Surface(SIZE, 0, display)
<span class="org-variable-name">begin_time</span> = time()
<span class="org-comment-delimiter">#</span><span class="org-comment">Needed for the camera to adjust brightness and focus</span>
<span class="org-variable-name">image</span> = cam.get_image()
<span class="org-keyword">while</span> time()-begin_time < 1.1:
<span class="org-variable-name">screen</span> = cam.get_image()
display.blit(screen, (0,0))
pygame.display.flip()
<span class="org-variable-name">image</span> = choose_best(image, screen)
cam.stop()
<span class="org-variable-name">pil_string_image</span> = pygame.image.tostring(image,<span class="org-string">"RGB"</span>,<span class="org-constant">False</span>)
<span class="org-variable-name">im</span> = Image.frombytes(<span class="org-string">"RGB"</span>, SIZE ,pil_string_image)
<span class="org-variable-name">out_file</span> = <span class="org-builtin">open</span>(file_name, <span class="org-string">'wb'</span>)
im.save(out_file, <span class="org-string">"JPEG"</span>)
<span class="org-comment-delimiter">#</span><span class="org-comment">from: http://discourse.techart.online/t/pil-wait-for-image-save/3994/6</span>
out_file.flush()
os.fsync(out_file)
out_file.close()
pygame.<span class="org-constant">quit</span>()
</pre>
</div>
</div>
</div>
<div id="outline-container-cropping_the_picture" class="outline-2">
<h2 id="cropping_the_picture"><span class="section-number-2">3</span> Cropping the picture</h2>
<div class="outline-text-2" id="text-3">
<p>
Again, I use pygame, using the code from these online answers:
<a href="https://coderwall.com/p/hmp8uw/image-cropping-using-pygame">https://coderwall.com/p/hmp8uw/image-cropping-using-pygame</a>
<a href="https://stackoverflow.com/questions/6136588/image-cropping-using-python/8696558">https://stackoverflow.com/questions/6136588/image-cropping-using-python/8696558</a>
</p>
<div class="org-src-container">
<pre class="src src-python"><span class="org-keyword">import</span> pygame
<span class="org-keyword">import</span> pygame.camera
<span class="org-keyword">from</span> pygame.<span class="org-builtin">locals</span> <span class="org-keyword">import</span> *
<span class="org-keyword">import</span> sys
<span class="org-keyword">from</span> PIL <span class="org-keyword">import</span> Image
<span class="org-keyword">import</span> os
<span class="org-comment-delimiter">#</span><span class="org-comment">https://coderwall.com/p/hmp8uw/image-cropping-using-pygame</span>
<span class="org-comment-delimiter">#</span><span class="org-comment">https://stackoverflow.com/questions/6136588/image-cropping-using-python/8696558 </span>
<span class="org-keyword">import</span> pygame, sys
<span class="org-keyword">from</span> PIL <span class="org-keyword">import</span> Image
pygame.init()
<span class="org-keyword">def</span> <span class="org-function-name">displayImage</span>(screen, px, topleft, prior):
<span class="org-comment-delimiter"># </span><span class="org-comment">ensure that the rect always has positive width, height</span>
<span class="org-variable-name">x</span>, <span class="org-variable-name">y</span> = topleft
<span class="org-variable-name">width</span> = pygame.mouse.get_pos()[0] - topleft[0]
<span class="org-variable-name">height</span> = pygame.mouse.get_pos()[1] - topleft[1]
<span class="org-keyword">if</span> width < 0:
<span class="org-variable-name">x</span> += width
<span class="org-variable-name">width</span> = <span class="org-builtin">abs</span>(width)
<span class="org-keyword">if</span> height < 0:
<span class="org-variable-name">y</span> += height
<span class="org-variable-name">height</span> = <span class="org-builtin">abs</span>(height)
<span class="org-comment-delimiter"># </span><span class="org-comment">eliminate redundant drawing cycles (when mouse isn't moving)</span>
<span class="org-variable-name">current</span> = x, y, width, height
<span class="org-keyword">if</span> <span class="org-keyword">not</span> (width <span class="org-keyword">and</span> height):
<span class="org-keyword">return</span> current
<span class="org-keyword">if</span> current == prior:
<span class="org-keyword">return</span> current
<span class="org-comment-delimiter"># </span><span class="org-comment">draw transparent box and blit it onto canvas</span>
screen.blit(px, px.get_rect())
<span class="org-variable-name">im</span> = pygame.Surface((width, height))
im.fill((128, 128, 128))
pygame.draw.rect(im, (32, 32, 32), im.get_rect(), 1)
im.set_alpha(128)
screen.blit(im, (x, y))
pygame.display.flip()
<span class="org-comment-delimiter"># </span><span class="org-comment">return current box extents</span>
<span class="org-keyword">return</span> (x, y, width, height)
<span class="org-keyword">def</span> <span class="org-function-name">setup</span>(path):
<span class="org-variable-name">px</span> = pygame.image.load(path)
<span class="org-variable-name">screen</span> = pygame.display.set_mode( px.get_rect()[2:] )
screen.blit(px, px.get_rect())
pygame.display.flip()
<span class="org-keyword">return</span> screen, px
<span class="org-keyword">def</span> <span class="org-function-name">mainLoop</span>(screen, px):
<span class="org-variable-name">topleft</span> = <span class="org-variable-name">bottomright</span> = <span class="org-variable-name">prior</span> = <span class="org-constant">None</span>
<span class="org-variable-name">n</span>=0
<span class="org-keyword">while</span> n!=1:
<span class="org-keyword">for</span> event <span class="org-keyword">in</span> pygame.event.get():
<span class="org-keyword">if</span> event.<span class="org-builtin">type</span> == pygame.MOUSEBUTTONUP:
<span class="org-keyword">if</span> <span class="org-keyword">not</span> topleft:
<span class="org-variable-name">topleft</span> = event.pos
<span class="org-keyword">else</span>:
<span class="org-variable-name">bottomright</span> = event.pos
<span class="org-variable-name">n</span>=1
<span class="org-keyword">if</span> topleft:
<span class="org-variable-name">prior</span> = displayImage(screen, px, topleft, prior)
<span class="org-keyword">return</span> ( topleft + bottomright )
<span class="org-keyword">if</span> <span class="org-builtin">__name__</span> == <span class="org-string">"__main__"</span>:
<span class="org-variable-name">input_loc</span> = <span class="org-builtin">str</span>(sys.argv[1])
<span class="org-variable-name">output_loc</span> = input_loc
<span class="org-variable-name">screen</span>, <span class="org-variable-name">px</span> = setup(input_loc)
<span class="org-variable-name">left</span>, <span class="org-variable-name">upper</span>, <span class="org-variable-name">right</span>, <span class="org-variable-name">lower</span> = mainLoop(screen, px)
<span class="org-comment-delimiter"># </span><span class="org-comment">ensure output rect always has positive width, height</span>
<span class="org-keyword">if</span> right < left:
<span class="org-variable-name">left</span>, <span class="org-variable-name">right</span> = right, left
<span class="org-keyword">if</span> lower < upper:
<span class="org-variable-name">lower</span>, <span class="org-variable-name">upper</span> = upper, lower
<span class="org-variable-name">im</span> = Image.<span class="org-builtin">open</span>(input_loc)
<span class="org-variable-name">im</span> = im.crop(( left, upper, right, lower))
pygame.display.<span class="org-constant">quit</span>()
<span class="org-variable-name">out_file</span> = <span class="org-builtin">open</span>(output_loc, <span class="org-string">'wb'</span>)
im.save(out_file, <span class="org-string">"JPEG"</span>)
<span class="org-comment-delimiter">#</span><span class="org-comment">from: http://discourse.techart.online/t/pil-wait-for-image-save/3994/6</span>
out_file.flush()
os.fsync(out_file)
out_file.close()
pygame.<span class="org-constant">quit</span>()
</pre>
</div>
</div>
</div>
<div id="outline-container-cleaning_the_image" class="outline-2">
<h2 id="cleaning_the_image"><span class="section-number-2">4</span> Cleaning the image</h2>
<div class="outline-text-2" id="text-4">
<p>
To clean the image, I was trying to remove the background by blurring the image, and dividing the original image by the blurred one.
</p>
<p>
This method is very effective. However, I found something even better, <a href="http://www.fmwconcepts.com/imagemagick/textcleaner/index.php">Fred's ImageMagick Scripts for text cleaning</a>.
</p>
</div>
</div>
<div id="outline-container-putting_it_all_together" class="outline-2">
<h2 id="putting_it_all_together"><span class="section-number-2">5</span> Putting it all together</h2>
<div class="outline-text-2" id="text-5">
<div class="org-src-container">
<pre class="src src-elisp">(<span class="org-keyword">defun</span> <span class="org-function-name">ivanaf/org-scan</span>(<span class="org-type">&optional</span> landscape)
(<span class="org-keyword">interactive</span>)
(<span class="org-keyword">let*</span> ((python-cam-command <span class="org-string">"~/org/packages/webcamscan/webcam.py"</span>)
(python-crop-command <span class="org-string">"~/org/packages/webcamscan/crop.py"</span>)
(text-command <span class="org-string">"~/org/packages/webcamscan/textcleaner"</span>)
(directory <span class="org-string">"./scan/"</span>)
(file-name (replace-regexp-in-string <span class="org-string">"\\."</span> <span class="org-string">""</span> (format <span class="org-string">"%s"</span> (float-time))))
(file-name (concat directory file-name <span class="org-string">".jpg"</span>))
(file-name (expand-file-name file-name))
(text-args
(<span class="org-keyword">if</span> landscape
<span class="org-string">"-l l -r cw -e normalize -s 1 -f 15 -o 5 -p 5 -u -T"</span>
<span class="org-string">" -r cw -e normalize -s 1 -f 15 -o 5 -p 5 -u -T"</span>))
(display-brightness-hw <span class="org-string">"/sys/class/backlight/intel_backlight/brightness"</span>)
(max-brightness <span class="org-string">"1500"</span>)
(cmd-file-name (shell-quote-argument file-name))
(brightness (shell-command-to-string (concat <span class="org-string">"cat "</span> display-brightness-hw)))
(brightness (replace-regexp-in-string <span class="org-string">"\n"</span> <span class="org-string">""</span> brightness)))
(make-directory directory t)
(shell-command (format <span class="org-string">"echo %s > %s"</span> max-brightness display-brightness-hw))
(shell-command (format <span class="org-string">"python3 %s %s"</span> python-cam-command cmd-file-name))
(shell-command (format <span class="org-string">"echo %s > %s"</span> brightness display-brightness-hw))
(shell-command (format <span class="org-string">"python3 %s %s"</span> python-crop-command cmd-file-name))
(shell-command (format <span class="org-string">"%s %s %s %s"</span> text-command text-args cmd-file-name cmd-file-name))
(insert <span class="org-string">"\n#+ATTR_ORG: :width 600\n"</span>)
(insert <span class="org-string">"#+attr_latex: :float nil\n"</span>)
(insert (concat <span class="org-string">"#+CAPTION: "</span> <span class="org-string">"\n"</span>))
(insert (concat <span class="org-string">"[[file:"</span> file-name <span class="org-string">"][file:"</span> file-name <span class="org-string">"]]"</span>))
(org-display-inline-images)))
(<span class="org-keyword">defun</span> <span class="org-function-name">ivanaf/org-scan-l</span>()
(<span class="org-keyword">interactive</span>)
(ivanaf/org-scan t))
(define-key org-mode-map (kbd <span class="org-string">"C-<print> "</span>) 'ivanaf/org-scan)
(define-key org-mode-map (kbd <span class="org-string">"M-<print> "</span>) 'ivanaf/org-scan-l)
</pre>
</div>
</div>
</div>
<div id="outline-container-results" class="outline-2">
<h2 id="results"><span class="section-number-2">6</span> Results:</h2>
<div class="outline-text-2" id="text-6">
<p>
Here is a "scan" of the back of the mit career fair book from last year, taken in my dark room.
</p>
<figure>
<a href="./jpg/15370864184127958.jpg"><img src="./jpg/15370864184127958.jpg" alt="15370864184127958.jpg"></a>
</figure>
<p>
Which is about as good as possible, give the quality of the light / camera.
</p>
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<div id="postamble" class="status">
<p class="author">Author: Ivan Tadeu Ferreira Antunes Filho</p>
<p class="date">Date: 2022-07-23 Sat 05:11</p>
<p class="author">Github: <a href="https://github.com/itf/">github.com/itf</a></p>
<p class="creator">Made with <a href="https://www.gnu.org/software/emacs/">Emacs</a> 27.1 (<a href="https://orgmode.org">Org</a> mode 9.3) and <a href="https://github.com/itf/org-export-head">Org export head</a> </p>
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