Skip to content
Switch branches/tags

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

Image Echelon


Image Echelon is a tool to quantify images where meaningful differences are discernible by eye, but difficult to quantify using traditional methods. It was developed to quantify neuronal fasciculation in microscopy images, but can be used to rank images based on any qualitative criteria. Classical methods ask observers to score an image in isolation along a scale (e.g., 1-5), which can be difficult to control between observers, especially in a highly variable data set. Image Echelon asks observers to compare two images and pick a “winner” and a “loser” along some criteria, an easier and more reliable task.

Users are presented with a landing page containing a written description of the phenomenon to be quantified, along with two example images: one clear “winner” and one clear “loser”. The software will then present two images randomly selected from the set, and the user is instructed to click on the “winner”.
Immediately after clicking, a new random pair is presented. This continues until the user terminates the program. After every iteration of these forced choice head-to-head match-ups, the score for each image is updated according to an Elo algorithm. This algorithm adds to the “winner” score and deducts from the “loser” score. The score held by each image entering the match-up determines the amount of points gained or lost: upsets (a low score image wins over a high score image) cause a greater point exchange than the converse.
This results in efficient ranking of the images long before every potential head-to-head match-up occurs. At any time, the researcher can extract a report in .csv format listing each image filename, along with its current score and number of match-ups, as well as a detailed report listing the result of every match-up. This detailed report lists the filename and score of both images after the match-up with the exact time the match-up was performed.

In Literature

In the paper Garret et al, Replacing the PDZ-interacting C-termini of DSCAM and DSCAML1 with epitope tags causes different phenotypic severity in different cell populations, eLife 2016;5:e16144 DOI: 10.7554/eLife.16144 PMID: 27637097 PMCID: PMC5026468, ImageEchelon was the software used for the ELO scoring mentioned under the Materials and methods section.


In order to use Image Echelon, you'll need to clone this repository to your server. An assumption is being made that you are either running from a linux environment (we use CentOS) or you are running on Mac OS X. We highly recommend running Image Echelon from a Python virtual environment. Image Echelon was implemented using Python 2 and 3. Before installing any other libraries you should make sure you have Python 2.7.9 or better (I'm currently running Python 3.4). The python package manager pip is included with this by default. Next you'll want to install virtualenv.

pip install virtualenv

Once installed you'll want to create a specific virtual environment for Image Echelon, like:

virtualenv ImageEchelon

This will create a new working directory named ImageEchelon (or whatever you chose to call the virtual environment). You'll then want to activate the virtual environment.

. ImageEchelon/bin/activate

Once your virtualenv is activated you will now use pip to install the required Python libraries. In the root directory of the project there is a requirements.txt file. To install the required packages simply run:

pip install -r requirements.txt

Configuration of ImageEchelon

The intent of ImageEchelon is to allow you to provide the service for comparing a set of images of your choosing. With that the text on the page will need to vary based on the image set.

Image Echelon uses an SQLite database that you will want to set up next. In order to setup a new database, first you need a directory of image files where the name of each file, prior to the extension (".png", ".jpg", ".jpeg") represents the name of the image.

# Image and Database configuration

# Web Configuration

# Text configuration
FULL_DESCRIPTION='Which image below more closely resembles the wild type?  Dendrites from wild type neurons evenly cover the field, while those from mutants bundle  together to form braided fascicles.  Once you click "Start Comparisons", select the image that is less fasciculated.'
HEAD_TEXT='Which image is less fasciculated?'
IMG_1_LABEL='Wild Type:'
IMG_1_TEXT='The dendrites evenly cover the entire field. GFP can fill individual dendrites, but is usually found in discrete puncta along their lengths.'
IMG_2_TEXT='The dendrites fasciculate, resulting in regions of dense labeling and regions of black space. GFP is less punctate in the dendrites.'

An example configuration file and image directory is located under the example directory.

Configuring and Setting up the database

You will need to change IMAGE_PATH to contain the location of your directory of images. You will also need to change DB to contain the location of where you would like your database to reside.

Once you have your configuration file you will need to set an environment variable called IMAGE_ECHELON_SETTINGS that will contain the location of the file. Than issue the following command:

IMAGE_ECHELON_SETTINGS=/etc/ImageEchelon.cfg python initdb

You can reset the scores in the database at anytime by deleting the database and re-running the above command. Note that this will eliminate all previous scores collected.

A simple schema of the database is

    image_id              INTEGER      unique image identifier
    name                  TEXT         unique name of file
    location              TEXT         location of file
    num_wins              INTEGER      number of times this image was picked
    num_losses            INTEGER      number of times this image was not picked
    updated               TEXT         date and time of last match 

    match_id              INTEGER      unique match identifier
    winner_id             INTEGER      unique image identifier of winner 
    loser_id              INTEGER      unique image identifier of loser
    updated               TEXT         date and time of match 

Configuring page text

The default text is specific to the the fasiculation of dendrites between wild type and mutant neurons. Obviously this doesn't meet the needs of all image sets.

The configuration file contains fields that can be configured. These fields include:

FULL_DESCRIPTION    -> This is the description under the ImageEchelon header.
HEAD_TEXT           -> This is the question text directly about the pair of images.
IMG_1_WIDTH         -> Size of the image width, set to 0 to use full size
IMG_1_HEIGHT        -> Size of the image width, set to 0 to use full size
IMG_1_LABEL         -> The label below the example image on the left.
IMG_1_TEXT          -> The description below the example image on the left.
IMG_1_DEFAULT       -> Example first image
IMG_2_WIDTH         -> Size of the image width, set to 0 to use full size
IMG_2_HEIGHT        -> Size of the image width, set to 0 to use full size
IMG_2_LABEL         -> The label below the example image on the right.
IMG_2_TEXT          -> The description below the example image on the right.
IMG_2_DEFAULT       -> Example second image

Configuring and Launching the web-application

To configure your web-application you should edit the configuration file:


The simplest way to launch the web application is as Python Flash application. From the src directory use the command:

IMAGE_ECHELON_SETTINGS=/etc/ImageEchelon.cfg python web

The application could also be run out of a separate web-server, but I will not detail how to do that here.

Statistics and Reporting

Once you have collected data, you can access your results from the following two URLs:


The first report returns a csv file containing the image file name, the rating and the number of match-ups that image was involved in. The second report returns the image file name, the last update date and the rating.

You could also run via the command line:

IMAGE_ECHELON_SETTINGS=/etc/ImageEchelon.cfg python reports

Two files will be created: rankings_report.tsv and detail_results.tsv.


Tool to quantify images where meaningful differences are discernible by eye, but difficult to quantify using traditional methods.




No releases published


No packages published