Instructions for document image quality evaluation

Introduction

Your task is to evaluate the subjective quality of strokes in document images compared to the non-degraded reference image. In the test, you should focus on the degree to which the structure of strokes are altered due to degradation. Two cues to degradation for this set of images include (1) Filled white connected component inside stroke. (2) The touching of separate strokes. Each HIT can be completed within 60 seconds.

Payment

We have methods that analyze the consistency of your answers with respect to themselves, to those of your fellow workers and to references we know to be accurate. We will use these methods to rank the submitted assignments according to quality.

For this experiment we will pay a base reward of $0.02/HIT for every accepted HIT. We have made available a set of 30 different HITs. You will receive a bonus of:

$0.03/HIT (for a total of $0.05/HIT) if you submit all 30 HITs or
$0.08/HIT (for a total of $0.10/HIT) if you submit all 30 HITs and your results are among the top 50% or
$0.18/HIT (for a total of $0.20/HIT) if you submit all 30 HITs and your results are among the top 10%.

Bonuses will be paid up to 7 days after submission, because we can only rank the submissions once we have a statistically significant number of answers. The base reward will always be paid within 24 hours of submission.

Instructions

Each file should be given a score according to the following scale, known as the MOS (mean opinion score) scale:

Score	Quality	Impairment
5	Excellent	The text is clear and easily readable. The strokes are sharp. White connected components are not filled. No touching strokes.
4	Good	Just perceptible smudged stroke, but not annoying.
3	Fair	Perceptible smudged stroke and slightly annoying.
2	Poor	Perceptible smudged stroke and very annoying.
1	Bad	The smudged stroke is impossible to be recognized.

The following references illustrate the meaning of each score. Please note that you may encounter other types of distortions. Therefore, these examples do not exhaust the range of conditions you can expect to see.

Examples

Reference score: 5.0
Non-degraded reference image.

Reference score: 4.0
Small White hole is paritally filled.

Reference score: 3.0
Separate strokes start touching, slightly annoying

Reference score: 2.0
Touching strokes and filled white connected components, very annoying

Reference score: 1
Shapes of characters are altered a lot due to smudging and the smudged stroke is impossible to be recognized.

Approval/Rejection Policy

Your results will be collected and evaluated for consistency. We (the requesters) have an estimate of each file's subjective quality that conforms with the references above. Thus, we can detect if someone submits random scores or does not rate according to these instructions, which can lead to work being rejected. You can rest assured that your work will be approved if you rate according to the table and examples above.

Answers will be either reviewed or automatically approved within 24 hours.