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Compression Image Quality Assessment Dataset (CIQA)

Overview

The CIQA dataset is an open-sourced collection of labels to the popular Aesthetic Visual Analysis (AVA) dataset. Images from AVA were sampled, compressed to different JPEG quality factors using the Tensorflow tf.image.adjust_jpeg_quality method and rated by human raters in a forced choice pairwise comparison study. This dataset is the result of the work in Deep Perceptual Image Quality Assessment for Compression

AVA Image Sampling

The Aesthetic Visual Analysis dataset (AVA) is well suited for deep learning applied to aesthetic Image Quality Assessment (IQA) proven by its successful implementation in the NIMA model. AVA contains ∼ 255,000 images rated based on aesthetic qualities by amateur photographers. Because these images are stored using JPEG compression, only the subset of images with a JPEG quality factor, Q, of 99 or more (near lossless) were sampled using the ImageMagick imaging tool software.

Sampled Image Compression

The sampled images are compressed at two random JPEG quality factors. The AVA dataset contains semantic labels in addition to perceptual quality rating. It is worth noting our sampling preserves the distribution of semantic classes. Semantic labels for each class of animal, architecture, cityscape, floral, food/drink, landscape, portrait, and still life have almost equal occurrence (∼ 6.25%). All reference images and the category of ’generic’ has an occurrence of 50%. This was done to ensure the diversity of sampled images and to create a more accurate representation of general perceptual image quality. Similarly, we preserve a wide distribution of resolutions from the sampled images which which varies from 200 × 200 to 800 × 800, and not necessarily always of equal height and width.

Labels

7808 pairwise comparisons were generated and each was rated by 32 individual participants. Pairs were chosen by compressing the reference image to two random JPEG quality factors from 10 to 100. 13,868 compressed images were generated from the 6,667 reference images. Of the 6,667 images sampled 6,372 reference images were used in the training set and 256 reference images were used in the training set. Each image in the training set was compressed with two different JPEG quality factors producing 1 pairwise comparison for each image and 6,372 total training examples. Each image in the test set was compressed with 4 different JPEG quality factors producing 6 pairwise comparisons for each reference image in the test set and 1536 total examples in the test set.

Resulting Dataset

The result is a dataset with a training set (6372 pairwise comparisons) and a test set (1536 pairwise comparisons). Column names in the data are

  • ref_id: The reference image ID from the AVA dataset
  • jpg1: This field is the first image's name formatted as {reference_image_id}/{jpg_Quality_Factor_1}.
  • jpg1: This field is the second image's name formatted as {reference_image_id}/{jpg_Quality_Factor_2}.
  • q1: The quality factor used to compress the first image from the reference image
  • q2: The quality factor used to compress the second image from the reference image
  • jpg2_pref: The label from 0.0 to 1.0 corresponding to the proportion of raters that prefered the second image. The proportion of raters who prefer the first image can be inferred as 1 - jpg2+pref

Access

The train and test sets are stored in the Google Research GCP public data storage. The data can be accessed through the gsutil CLI, tf.io.gfile API and HTTP api. It is stored in gs://gresearch bucket under the CIQA directory.