The Supernote A5X is an e-ink notebook that lets me draw in black, white, and two shades of gray. It has a drawing app that supports other shades of gray, but the main notebook app and the PDF annotation is limited to those two shades of gray.

I like to use a dotted grid in order to write in neat lines. I used to manually change this template to a white one before exporting. Then it occurred to me to make a coloured template:

Using colour lets me use a darker grid, which is more visible on the Supernote, while still letting that grid blend into the background if I export without processing. Screen mirroring shares the grayscale version, though.

I use my recoloring script to change #a6d2ff (light blue) to #ffffff (white).

Here's the SVG source in case you want to customize it. When I exported the PNG from Inkscape, I needed to make sure that antialiasing was turned off. This involved unchecking the "Hide export settings" checkbox in the Export dialog, then setting Antialias to 0. source

My current color scheme is 9d9d9d,c2c2c2,c9c9c9,f6f396,cacaca,f6f396,a6d2ff,ffffff', which maps light gray to a highlighter sort of yellow and dark gray to a light gray. I used to map the dark gray to a dark red like the links on my site, but light gray is more flexible for shading and layout.

Anyway, here's an example of the export from my Supernote and the result after processing:

(This sketch is How to Take Smart Notes, one of my visual book notes.)

I use a CSS rule to invert my sketch colours when viewed in dark mode:

@media (prefers-color-scheme: dark) {
    .sketch-full img, .gallery img, .left-doodle, .right-doodle, .center-doodle { filter: invert(1) hue-rotate(180deg) brightness(150%) contrast(0.9); }
}

which is not fine-tuned or amazing, but it reduces the glare from the white background when I browse on my phone at night.

Sometimes I switch things around and use blue/dark blue instead. I now have some Emacs Lisp code to let me somewhat interactively recolour a sketch from the Emacs text editor so that I can change the colours in a sketch as I'm writing a post about it.

Using a coloured template and a script to change the colours around has made my Supernote workflow more convenient. I don't need to change the template on new pages. I just export the image, sync with Dropbox or use the Browse & Access feature, and run my processing script. My processing script also uses Google Cloud Vision to recognize the text, rename the sketch, and file it in the appropriate directory, so it's pretty smooth. It's pretty idiosyncratic, but maybe you might be able to adapt the ideas to your own setup. Hope this helps!

I've been experimenting with the Supernote's Browse and Access feature because I want to be able to upload files quickly instead of waiting for Dropbox to synchronize. First, I want to store the IP address in a variable:

(defvar my-supernote-ip-address "192.168.1.221")

Here's how to upload:

(defun my-supernote-upload (filename &optional supernote-path)
  (interactive "FFile: ")
  (setq supernote-path (or supernote-path "/INBOX"))
  (let* ((boundary (mml-compute-boundary '()))
         (url-request-method "POST")
         (url-request-extra-headers
          `(("Content-Type" . ,(format "multipart/form-data; boundary=%s" boundary))))
         (url-request-data
          (mm-url-encode-multipart-form-data
           `(("file" . (("name" . "file")
                        ("filename" . ,(file-name-nondirectory filename))
                        ("content-type" . "application/octet-stream")
                        ("filedata" . ,(with-temp-buffer
                                         (insert-file-contents-literally filename)
                                         (buffer-substring-no-properties (point-min) (point-max)))))))
           boundary)))
    (with-current-buffer
        (url-retrieve-synchronously
         (format "http://%s:8089%s" my-supernote-ip-address supernote-path))
      (re-search-backward "^$")
      (prog1 (json-read)
        (kill-buffer)))))

HTML isn't supported. Text works, but it doesn't support annotation. PDF or EPUB could work. It would make sense to register this as an export backend so that I can call it as part of the usual export process.

(defun my-supernote-org-upload-as-text (&optional async subtree visible-only body-only ext-plist)
  "Export Org format, but save it with a .txt extension."
  (interactive (list nil current-prefix-arg))
  (let ((filename (org-export-output-file-name ".txt" subtree))
        (text (org-export-as 'org subtree visible-only body-only ext-plist)))
    ;; consider copying instead of exporting so that #+begin_export html etc. is preserved
    (with-temp-file filename
      (insert text))
    (my-supernote-upload filename)))

(defun my-supernote-org-upload-as-pdf (&optional async subtree visible-only body-only ext-plist)
  (interactive (list nil current-prefix-arg))
  (my-supernote-upload (org-latex-export-to-pdf async subtree visible-only body-only ext-plist)))

(defun my-supernote-org-upload-as-epub (&optional async subtree visible-only body-only ext-plist)
  (interactive (list nil current-prefix-arg))
  (my-supernote-upload (org-epub-export-to-epub async subtree visible-only ext-plist)))

(org-export-define-backend
    'supernote nil
    :menu-entry '(?s "Supernote"
                     ((?s "as PDF" my-supernote-org-upload-as-pdf)
                      (?e "as EPUB" my-supernote-org-upload-as-epub)
                      (?o "as Org" my-supernote-org-upload-as-text))))

Adding this line to my Org file allows me to use \spacing{1.5} for 1.5 line spacing, so I can write in more annotations..

#+LATEX_HEADER+: \usepackage{setspace}

Sometimes I use custom blocks for HTML classes. When LaTeX complains about undefined environments, I can define them like this:

#+LATEX_HEADER+: \newenvironment{whatever_my_custom_environment_is_called}

Now I can export a subtree or file to my Supernote for easy review.

I wonder if multimodal AI models can handle annotated images with editing marks…

I want to quickly get drawings from my Supernote A5X into Emacs so that I can include them in blog posts. Dropbox/Google Drive sync is slow because it synchronizes all the files. The Supernote can mirror its screen as an .mjpeg stream. I couldn't figure out how to grab a frame from that, but I did find out how to use Puppeteer to take an screenshot of the Supernote's screen mirror. Still, the resulting image is a little pixelated. If I turn on Browse and Access, the Supernote can serve directories and files as webpages. This lets me grab the latest file and process it. I don't often have time to fill a full A5 page with thoughts, so autocropping the image encourages me to get stuff out there instead of holding on to things.

(defvar my-supernote-ip-address "192.168.1.221")
(defun my-supernote-get-exported-files ()
  (let ((data (plz 'get (format "http://%s:8089/EXPORT" my-supernote-ip-address)))
        (list))
    (when (string-match "const json = '\\(.*\\)'" data)
      (sort
       (alist-get 'fileList (json-parse-string (match-string 1 data) :object-type 'alist :array-type 'list))
       :key (lambda (o) (alist-get 'date o))
       :lessp 'string<
       :reverse t))))

(defun my-supernote-org-attach-latest-exported-file ()
  (interactive)
  ;; save the file to the screenshot directory
  (let ((info (car (my-supernote-get-exported-files)))
        new-file
        renamed)
    ;; delete matching files
    (setq new-file (expand-file-name
                    (replace-regexp-in-string " " "%20" (alist-get 'name info) (org-attach-dir))))
    (when (file-exists-p new-file)
      (delete-file new-file))
    (org-attach-attach
     (format "http://%s:8089%s" my-supernote-ip-address
             (alist-get 'uri info))
     nil
     'url)
    (setq new-file (my-latest-file (org-attach-dir)))
    ;; recolor
    (my-sketch-recolor-png new-file)
    ;; autocrop that image
    (my-image-autocrop new-file)
    ;; possibly rename
    (setq renamed (my-image-recognize-get-new-filename new-file))
    (when renamed
      (setq renamed (expand-file-name renamed (org-attach-dir)))
      (rename-file new-file renamed t)
      (my-image-store renamed) ; file it in my archive
      (setq new-file renamed))
    ;; use a sketch link if it has an ID
    (if (string-match "^[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]-[0-9][0-9] "
                      (file-name-base renamed))
        (org-insert-link nil (concat "sketchFull:" (file-name-base renamed)))
      ;; insert the link
      (org-insert-link nil (concat "attachment:" (replace-regexp-in-string "#" "%23" (file-name-nondirectory new-file)))))
    (org-redisplay-inline-images)))

[2024-09-13 Fri] I added a mogrify call to automatically trim the image.

Partly inspired by John Kitchin's video showing how to copy screenshots from his iPad and do optical character recognition so he can use the images and text in Org Mode, I'd like to be able to draw quick notes while I'm thinking through a topic on my computer.

Krita might work, but it's awkward to draw on my tablet PC's screen when it's in laptop mode because of the angle. Flipping it to tablet mode is a bit disruptive.

I can draw on my Supernote, which feels a bit more natural. I have a good workflow for recoloring and renaming exported sketches, but exporting via Dropbox is a little slow since it synchronizes all the folders. The SuperNote has a built-in screen mirroring mode with an MJPEG that I can open in a web browser. Saving it to an image is a little complicated, though. ffmpeg doesn't work with the MJPEG that it streams, and I can't figure out how to get stuff out aside from using a browser. I can work around this by using Puppeteer and getting a screenshot. Here's a NodeJS snippet that saves that screenshot to a file.

/* This file is tangled to ~/bin/supernote-screenshot.js from my config at https://sachachua.com/dotemacs
Usage: supernote-screenshot.js [filename]
Set SUPERNOTE_URL to the URL.
*/

const process = require('process');
const puppeteer = require('puppeteer');
const url = process.env['SUPERNOTE_URL'] || 'http://192.168.1.221:8080/screencast.mjpeg';
const scale = 0.5;
const delay = 2000;

async function takeSupernoteScreenshot() {
  const browser = await puppeteer.launch({headless: 'new'});
  const page = await browser.newPage();
  await page.setViewport({width: 2808 * scale, height: 3744 * scale, deviceScaleFactor: 1});
  page.goto(url);
  await new Promise((resolve, reject) => setTimeout(resolve, delay));
  let filename = process.argv[2] || 'screenshot.png';
  await page.screenshot({type: 'png', path: filename, fullPage: true});
  await browser.close();
}

takeSupernoteScreenshot();

Then I can call that from Emacs Lisp and run it through my usual screenshot insertion process:

(defun my-org-insert-supernote-screenshot-from-mirror ()
  "Copy the current image from the SuperNote mirror."
  (interactive)
  (let ((filename (expand-file-name (format-time-string "%Y-%m-%d-%H-%M-%S.png") "~/recordings")))
    (shell-command-to-string (concat "NODE_PATH=/usr/lib/node_modules node ~/bin/supernote-screenshot.js " (shell-quote-argument filename)))
    ;; trim it
    (call-process "mogrify" nil nil nil "-trim" "+repage" filename)
    (shell-command-to-string (concat "~/bin/recolor.py --colors c0c0c0,f6f396 " (shell-quote-argument filename)))
    (call-interactively 'my-org-insert-screenshot)))

[2024-09-13 Fri] I already have some code elsewhere for using the Google Cloud Vision API to extract text from an image, so I should hook that up sometime. Also, OpenAI supports multimodal requests, so I've been thinking about using AI to recognize text and diagrams like in this Supernote to Markdown example. Fun fun fun!

Both Google Cloud Vision and SuperNote's new handwriting recognition handle my print fine. Neither handle columns the way I'd like, but to be fair, I'm not really sure how I want columns and wrapping handled anyway. I can always experiment with the standard use-case: one column of text, to export as text (with perhaps the occasional sketch, which I can crop and include).

If I can get the hang of writing my thoughts, then it turns some of those bedtime hours into writing hours. Writing by hand feels slow and linear, but it's better than nothing, and thinking takes most of the time anyway. While speech recognition feels like it might be faster in short bursts, I don't have a lot of "talking to myself" time (aside from sleepy brain dumps), and my workflow for processing audio is still slow and disjointed. I can't type on my phone because then A- will want to be on a screen too. I'm glad e-ink devices are different enough not to trigger her sense of unfairness, although sometimes she does ask if she can do mazes or connect-the-dots. Then I switch to knitting until it's really really time to go to bed.

I'm slowly figuring out my workflows for experimenting with and writing about code. Naturally, that's a little more challenging to write about by hand, but I could draft the context. I can think through life stuff too, and maybe look into saving more notes in my Org files.

I've experimented with handwritten blog posts before. Now that I have a little more time to tweak my workflow and think thoughts, maybe I'll get the hang of them!

It looks like the Supernote's real-time recognition is pretty accurate for my handwriting, getting the text out of multiple pages is pretty straightforward.

Here's the raw TXT output from the Supernote.

Here's what it took to edit it into the first part of this post - just adding line-breaks and fixing up some words:

Source images

[[

If I add more lines between paragraphs when writing, I might be able to skip adding them in the text export.

For comparison, here's the text output from Google Cloud Vision.

Tweaking my handwriting workflow
Both Google Cloud Vision and Super Note's new
handwriting recognition handle my print fine. Neither
handle columns the way I'd like, but to be fair,
I'm not really sure how I want columns and wrapping
handled anyway I can always experiment with the
standard use-case
use-case: One column of text, to export
as Text (with perhaps the occasional sketch, which
can crop and include).
If I can get the hang of writing my thoughts,
then it turns some of those bedtime hours into writi
writing
hours. Writing by hand feels slow and linear, but it's
better than nothing, and thinking takes most of the time
anyway while speech recognition feels like it might be
faster in short bursts, don't have a lot of "talking to
myself" time (aside from sleepy braindumps), and my workflow
for processing audio is still slow and disjointed. I can't
type on my phone because then A- will want to be on

I'm glad e-ink devices are different enough
not to trigger her sense of unfairness, although sometimes
she does ask if she can do mazes or connect-the-dots
a screen too
Then I switch to Knitting until it's really really time to
go to bed.
I'm slowly figuring out my workflows for experimenting
with and writing about code. Naturally, that's a little
more challenging to write about by hand, but I could
draft the context. I can think through life stuff too, and
maybe look into saving more notes in my org files
I've experimented with handwritten blog posts before
Now that I have a little more time to tweak my workflow
and think thoughts, maybe I'll get the hang of them!

I'm leaning towards SuperNote's recognition results for long text, although I don't get access to the confidence data so I'll probably just have to delete the misrecognized text if I include sketches.

I want to make it easier to process the sketchnotes I make on my Supernote. I write IDs of the form yyyy-mm-dd-nn to identify my sketches. To avoid duplicates, I get these IDs from the web-based journaling system I wrote. I've started putting the titles and tags into those journal entries as well so that I can reuse them in scripts. When I export a sketch to PNG and synchronize it, the file appears in my ~/Dropbox/Supernote/EXPORT directory on my laptop. Then it goes through this process:

• I use Google Cloud Vision to detect handwriting so that I can find the ID.
  • I retrieve the matching entry from my journal system and rename the file based on the title and tags.
  • If there's no matching entry, I rename the file based on the ID.
• If there are other tags or references in the sketch, I add those to the filename as well.
• I recolor it based on the tags, so parenting-related posts are a little purple, tech/Emacs-related posts are blue, and things are generally highlighted in yellow otherwise.
• I move it to a directory based on the tags.
  • If it's a private sketch, I move it to the directory for my private sketches.
  • If it's a public sketch, I move it to the directory that will eventually get synchronized to sketches.sachachua.com, and I reload the list of sketches after some delay.

The following code does that processing.

Download supernote-daemon

#!/usr/bin/python3
# -*- mode: python -*-

# (c) 2022-2023 Sacha Chua (sacha@sachachua.com) - MIT License

# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.


import os
import json
import re
import requests
import time
from dotenv import load_dotenv
# Import the Google Cloud client libraries
from google.cloud import vision
from google.cloud.vision_v1 import AnnotateImageResponse
import sys
sys.path.append("/home/sacha/proj/supernote/")
import recolor   # noqa: E402  # muffles flake8 error about import
load_dotenv()


# Set the folder path where the png files are located
folder_path = '/home/sacha/Dropbox/Supernote/EXPORT/'
public_sketch_dir = '/home/sacha/sync/sketches/'
private_sketch_dir = '/home/sacha/sync/private-sketches/'

# Initialize the Google Cloud Vision client
client = vision.ImageAnnotatorClient()
refresh_counter = 0

def extract_text(client, file):
    json_file = file[:-3] + 'json'
    # TODO Preprocess to keep only black text
    with open(file, 'rb') as image_file:
        content = image_file.read()
    # Convert the png file to a Google Cloud Vision image object
    image = vision.Image(content=content)

    # Extract handwriting from the image using the Google Cloud Vision API
    response = client.document_text_detection(image=image)
    response_json = AnnotateImageResponse.to_json(response)
    json_response = json.loads(response_json)
    # Save the response to a json file with the same name as the png file
    with open(json_file, "w") as f:
        json.dump(json_response, f)


def maybe_rename(file):
    # TODO Match on ID
    json_file = file[:-3] + 'json'
    with open(json_file, 'r') as f:
        data = json.load(f)

    # Extract the text from the json file
    text = data['fullTextAnnotation']['text']

    # Check if the text contains a string matching the regex pattern
    pattern = r'(?<!ref:)[0-9]{4}-[0-9]{2}-[0-9]{2}-[0-9]{2}'
    match = re.search(pattern, text)
    if match:
        # Get the matched string
        matched_string = match.group(0)
        new_name = matched_string
        from_zid = get_journal_entry(matched_string).strip()
        if from_zid:
            new_name = matched_string + ' ' + from_zid
        tags = get_tags(new_name, text)
        if tags:
            new_name = new_name + ' ' + tags
        ref = get_references(text)
        if ref:
            new_name = new_name + ' ' + ref
        print('Renaming ' + file + ' to ' + new_name)
        # Rename the png and json files to the matched string
        new_filename = os.path.join(os.path.dirname(file), new_name + '.png')
        rename_set(file, new_filename)
        return new_filename


def get_tags(filename, text):
    tags = re.findall(r'(^|\W)#[ \n\t]+', text)
    return ' '.join(filter(lambda x: x not in filename, tags))


def get_references(text):
    refs = re.findall(r'!ref:[0-9]{4}-[0-9]{2}-[0-9]{2}-[0-9]{2}', text)
    return ' '.join(refs)


def get_journal_entry(zid):
    resp = requests.get('https://' + os.environ['JOURNAL_USER']
                        + ':' + os.environ['JOURNAL_PASS']
                        + '@journal.sachachua.com/api/entries/' + zid)
    j = resp.json()
    if j and not re.search('^I thought about', j['Note']):
        return j['Note']


def get_color_map(filename, text=None):
    if text:
        together = filename + ' ' + text
    else:
        together = filename
    if re.search('r#(parenting|purple|life)', together):
        return {'9d9d9d': '8754a1', 'c9c9c9': 'e4c1d9'}  # parenting is purplish
    elif re.search(r'#(emacs|geek|tech|blue)', together):
        return {'9d9d9d': '2b64a9', 'c9c9c9': 'b3e3f1'}  # geeky stuff in light/dark blue
    else:
        return {'9d9d9d': '884636', 'c9c9c9': 'f6f396'}  # yellow highlighter, dark brown


def rename_set(old_name, new_name):
    if old_name != new_name:
        old_json = old_name[:-3] + 'json'
        new_json = new_name[:-3] + 'json'
        os.rename(old_name, new_name)
        os.rename(old_json, new_json)


def recolor_based_on_filename(filename):
    color_map = get_color_map(filename)
    recolored = recolor.map_colors(filename, color_map)
    # possibly rename based on the filename
    new_filename = re.sub(' #(purple|blue)', '', filename)
    rename_set(filename, new_filename)
    recolored.save(new_filename)


def move_processed_sketch(file):
    global refresh_counter
    if '#private' in file:
        output_dir = private_sketch_dir
    elif '#' in file:
        output_dir = public_sketch_dir
        refresh_counter = 3
    else:
        return file
    new_filename = os.path.join(output_dir, os.path.basename(file))
    rename_set(file, new_filename)
    return new_filename


def process_file(file):
    json_file = file[:-3] + 'json'
    # Check if a corresponding json file already exists
    if not os.path.exists(json_file):
        extract_text(client, file)
    if not re.search('[0-9]{4}-[0-9]{2}-[0-9]{2}-[0-9]{2} ', file):
        file = maybe_rename(file)
    recolor_based_on_filename(file)
    move_processed_sketch(file)


def process_dir(folder_path):
    global processed_files
    # Iterate through all png files in the specified folder
    files = sorted(os.listdir(folder_path))
    for file in files:
        if file.endswith('.png') and '_' in file:
            print("Processing ", file)
            process_file(os.path.join(folder_path, file))


def daemon(folder_path, wait):
    global refresh_counter
    while True:
        process_dir(folder_path)
        time.sleep(wait)
        if refresh_counter > 0:
            refresh_counter = refresh_counter - 1
            if refresh_counter == 0:
                print("Reloading sketches")
                requests.get('https://' + os.environ['JOURNAL_USER'] + ':'
                             + os.environ['JOURNAL_PASS']
                             + '@sketches.sachachua.com/reload?python=1')


if __name__ == '__main__':
    # Create a set to store the names of processed files
    processed_files = set()
    if len(sys.argv) > 1:
        if os.path.isdir(sys.argv[1]):
            folder_path = sys.argv[1]
            daemon(folder_path, 300)
        else:
            for f in sys.argv[1:]:
                process_file(f)
    else:
        daemon(folder_path, 300)

It uses this script I wrote to recolor my sketches with Python.

I'm contemplating writing some annotation tools to make it easier to turn the detected text into useful text for searching or writing about because the sketches throw off the recognition (misrecognized text, low confidence) and the columns mess up the line wrapping. Low priority, though.

My handwriting (at least for numbers) is probably simple enough that I might be able to train Tesseract OCR to process that someday. And who knows, maybe some organization will release a pre-trained model for offline handwriting recognition that'll be as useful as OpenAI Whisper is for audio files. That would be neat!