This is a benchmark dataset of natural object-based images with attribute annotations – the aPascal-aYahoo data set3 – which is introduced by Farhadi et al. The aPascal-aYahoo data set has two subsets: the Pascal VOC 2008 dataset and the aYahoo dataset. The Pascal VOC 2008 dataset is created for visual object classifications and detections. The aPascal data set covers 20 attribute-labelled classes and each class contains a number of samples, ranging from 150 to 1000. The aYahoo dataset, as a supplement of the aPascal dataset, contains objects similar to aPascal, but with different correlations between attributes. The aYahoo dataset only contains 12 objects classes. Images in both aPascal and aYahoo sets are annotated with 64 binary attributes, covering shape and material as well as object components.