the Personal Columbia images are recorded. RAW format image is
the direct output from the CCD sensor and therefore can be used to
generate images with different in-camera image processing operations
such as white-balancing, sharpening, contrast adjustment and nonlin-
ear transformation, as well as image compression. See Subsection 5.1.1
for more details.
8. For evaluating the robustness of the classifier with respect
to the computer graphics rendering techniques: When the al-
gorithm of the classifier is known, adversarial attack specific to the
algorithm can be designed to manipulate the output of the classifier.
For example, if the classifier is known for recognizing PRCG by the
high color saturation, attackers can reduce the color saturation of a
PRCG such that it is classified as a photographic image. Due to the
dependency of an adversarial attack upon the specific algorithm, it is
hard for our dataset to meet the specific needs from evaluating the
classifier robustness against such attack.
9. For evaluating sensitivity to ambiguity in content and camera
effects: In Personal Columbia set, there are images of artificial objects
such as drawing, sculpture, wax figures, fake fruit for decoration, and
so on. In the PRCG set, we have images of natural scenes such as
forest, ponds, seaside as well as images of building. Furthermore, the
simulation of the camera effects such as the depth-of-field (DoF) effect
in the PRCG also results in an ambiguity in terms of camera effects.
4 The PRCG Set
This section will describe the acquisition process of the 800 PRCG in our
dataset. The following list shows the properties of the PRCG set:
1. Reliable Sources: The images are downloaded from the profes-
sional 3D artist websites on the Internet such as www.softimage.com,
www.3ddart.org, www.3d-ring.com and so on. Unfortunately, there
are websites where people submit photographic images and claim to be
PRCG. One characteristic of these unreliable websites is that the sub-
mitted PRCG are often from anonymous persons or by people identify
themselves by nicknames. Therefore, we only download the trustable
PRCG, submitted together with the creator's name, contact informa-
tion. Table 1 shows the major online sources for the PRCG set.
8