Annotating Images of Faces with ImageStats

Skin Annotation Task

This page last updated Jan 11th.

Deadline has passed to claim ImageStats tasks
As previously announced, 23:00 UTC Friday, January 11, was the deadline. Unclaimed tasks have been removed.

ImageStats was updated Friday, Jan. 4. Changes in features or procedures are highlighted by - NEW - below. An additional update Monday, Jan. 7, is highlighted by - NEWEST -

Displaying your Images

With ImageStats open, in the left-hand side, there is the “Event List”. You should see just your specific task, e.g. Skin 02_03.

- NEW - To the right, in the “Search” results, you will see a list of images with anonymized filenames.

(In previous configurations of ImageStats, you had to first put a checkmark in your task's box, then hit “Search” [without altering what’s in the Search text field, “:”.])

Above them is a row of “Export” related controls. You will not need to use these except when you’ve completed your task.

Handling Each Picture - Key Steps

  1. Open picture. (- NEW - There are no longer existing annotations that need clearing.)
  2. Find & draw skin annotations
  3. Either:
    • “Save” & “Close”
    • “Save” & “Next” (recommended) - NEW -

Handling Each Picture - Details

1) Open Picture

To open a picture, either:

  • double-click on it from a Search results page
  • - NEW - navigate to it from a previously open picture using the “Next” or “Previous” button. These buttons move in sequence through all the pictures shown within the current page of the Search results. In the case of “Next”, once you come to the last image in the current page, the button will be disabled, and you must use Save & Close instead, then change the Search results page. Similarly for “Previous”.

- NEW - Once open, an image will have no rectangular annotations (aka “boxes”) initially. (If you are revisiting an image you annotated earlier, see “Revisiting a Photo - Why Don't I See My Annotations?” below.)

Note. This situation differs from the Face Annotation task, where

  • initial yellow or red boxes can appear after a second or two, from a computer “FaceFinder/FaceMatch” algorithm.
  • the “Restore FaceFinder” button is enabled.

(In previous versions of ImageStats, even for the skin tasks, initial yellow or red boxes could appear from the “FaceMatch” algorithm. You would have to hit “Clear all boxes” to remove these.)

2) Find & Draw Skin Annotations

Always select the “skin” radio button for drawing, which will provide blue rectangles.

For details of how to draw bounding boxes, see

- NEW - The radio buttons like “skin” now control not just the drawing choice, but what type of boxes you see. To see the blue (specifically cyan) skin boxes, you must select either “skin” or “show all”. Editing is not possible in “show all” mode.

- NEW - You are not allowed to draw any box edge outside the picture boundary. (This solves a bug affecting “Save” in previous versions.)

You are looking for areas of exposed skin that can be sampled with rectangular annotations. When choosing where to put a rectangle, the most important thing is to avoid including any “non-skin” colors, associated with:

  • hair
  • clothing
  • objects or surroundings
  • eyes
  • lips (with or without lipstick)
  • highly-colored makeup such as eyeliner
  • body paint or tattoos

It is OK to include skin with subtle makeup.

Typical places to consider are the forehead, cheeks, neck, arms, and back of hands. Some shots include leg or torso skin as well. 3-6 samples per person would be ideal.

- NEW - Overlap between annotations is permissible and sometimes necessary, but try to avoid it or minimize its extent as much as possible.

Two Approaches You Can Use.

A. Look for skin patches that are relatively small (though not tiny) and roughly uniform in color, that is, relatively free from lighting effects and detailed facial structures. Many annotations in the example pictures below are in this style.

B. Use somewhat larger patches, with more straddling across shadows and body structures. So a rectangle could span left cheek + nose bridge + right cheek (as in the right-hand photo below), or chin + neck + upper chest.


If you make a mistake on an image, start over with “Clear all boxes”, or delete an individual box as explained in Help.

- NEWEST - When drawing or resizing a box for a Skin task, height and width can be any size (except zero). This differs from Face tasks, which have more obvious minimum box heights and widths imposed.

- NEW -. You can no longer “delete” a box in an invalid manner by resizing a dimension to zero.

“Restore Final” could also be used if you are revisiting an image you did earlier, started to revise it, then changed your mind.

Problematic Photos. Occasionally, there will be a photo where few or no annotations are possible. In particular, skip any annotations for photos that are:

  • black & white (or a toned version)
  • false-color
  • hand-tinted
  • taken under highly-colored artificial lighting conditions
3) "Save" & "Close" or "Save" & "Next"

When done with an image, hit “Save”, then either:

  • “Close” to return to the Search page.
  • “Next” to navigate to the next picture seen within the current Search-results page. - NEW -

VERY IMPORTANT: You must hit “Save”, in order for your review work to be recorded. “Close” or “Next” alone is not enough.

Be sure to save and close your current image before logging-out.

Pausing and Resuming Your Work within a Task, Between Photos

Images that have already been annotated by you should have a green border; ones not yet done should have a gray border. Resume with the first gray one.

Revisiting a Photo - Why Don't I See My Annotations?

Revising a photo is not normally necessary, unless, say, you annotated a b&w photo when you shouldn't have. If you do return to a photo, once again you see no annotations. To see your earlier annotation work:

  • - NEW - Select either “skin” or “show all” mode
  • hit “Restore Final”

(- NEW - Earlier guidance about how to revisit a photo to remove leftover red or yellow boxes is dropped as superfluous.)

Submitting a Completed Task

After you save and close the last image, you must submit the task as completed as follows:

  1. In the Export type control, select “Final GroundTruthData to TSV file”
  2. Hit the “Export All Results” button, and save the file on your local disk. The file name should automatically reflect the task name and “Final”. If there is any problem with the “Export All Results” button, try hitting the “Search” button up above first to list the images again.
  3. Optional: you can verify the file contents by opening it in a text editor. The expected content is discussed in the next section.
  4. Copy the file name to the Melange “Upload” field, then hit the Upload button.
  5. Change the Melange status for the task to “Ready for Review”.

(- NEW - Previous guidance, now considered unnecessary, suggested also sending a message to with a subject line like “Task Done: Skin 01 03” and the file attached.)

Expect an acknowledgement within 24 hours, and, after QA, an acceptance within 3 days.

Expected File Format

There will be 1 line for each image visited and “Saved”. Routinely a task will contain 399 images, in which case there should be at least 399 lines in the file.

Each line in the file must contain these fields:

  • an identifier
  • an url
  • a username followed by a filename
  • zero or more annotations of form s[x,y;w,h]

Multiple annotations in a line are separated by tabs. The first letter of an annotation will be “s” for “skin”. Within the brackets, the first two integers will be the coordinates within the photo of the box's upper-left corner, followed by the width and height, all in pixels.

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