Photographic cropping as a paradigm for
experimental aesthetics
Assessing the role of individual differences, colour, meaning and expertise
Chris McManus, Anita Zhou, Sophie I'Anson & Lucy Waterfield
UCL Research Department of Clinical, Educational and Health Psychology, University College London, Gower Street, London WC1E 6BT, UK
Gustav Theodor Fechner’s Vorschule der
Aesthetik of 1876 introduced the three main
methods used in experimental aesthetics:
● The Method of Choice
● The Method of Use
● The Method of Production
The least popular method, despite its
theoretical attractions, has been the Method
of Production, in which participants produce
objects that they regard as aesthetically
attractive. The problem is mainly practical,
most subjects not having sufficient technical
ability at drawing or other skills.
Photography solves that problem. People
are used to taking photographs, often
making decisions on how to frame a subject
in the viewfinder, or to crop a larger
photograph to a smaller. People also agree
that some photographs are aesthetically
superior. The main practical problem in using
real photography is that there are too many
degrees of freedom – camera position,
zoom, focus, aspect ratio, and shutter timing.
These studies therefore are restricted to the
cropping of photographs (and in some
sense a photograph ‘crops’ the visual world).
Cropping is part of the broader aesthetic
problem of composition, arranging objects
in relation to each other and a frame to
produce an attractive outcome. Such
questions were considered by Denman
Ross’ Theory of Pure Design of 1907, and
Rudolf Arnheim’s Art and Visual Perception
of 1954, but not applied to photographs.
Our computer task was designed to parallel
the ways in which photographs are taken.
Method
Subjects firstly saw a 1024 x 768 pixel
photograph on a computer screen (see
figure 1). This Viewing window also
contained a yellow Inclusion box, which
was a part of the image that had to be
included in the final crop (the ‘subject’ in
some sense). A click on the mouse button
opened a 512 x 384 Crop window (half the
linear extent and a quarter the area) the
original), through which the image could be
seen. Instructions were purposely minimal,
asking subjects to move the crop window
until the cropped image picture looked “as
good as possible”. Subjects found the task
intuitive and natural (and indeed, they often
also described it as fun and interesting).
Fig 1: a) original image; b) Viewing
Window; c & d) possible Crop Windows
a)
c)
b)
d)
Results
Figure 2 shows a typical set of croppings
of an image by 41 non-expert subjects.
The large yellow box is the bound for
possible crops given the position of the
inclusion box. Individual croppings are
shown as pastel-coloured boxes, red
squares show the centre of each
subject’s crop window, and the red box is
the ‘median cropping window’.
Fig 2: Crop windows chosen by 41 nonexpert subjects.
The five studies addressed key questions
about the psychometrics of cropping.
Study 1: Do subjects differ and are
those differences reliable?
20 ‘croppers’ cropped 40 images, and
then immediately cropped the same 40
images again. Although croppers showed
large individual differences, the median
crop location for images did not differ
across occasions, and subjects were
reliable across occasions (mean imagelevel correlations: .614 (H) and .562 (V)).
Subjects find cropping an acceptable task
that they carry out consistently.
Studies 2 & 3: Are some people better
croppers than others (i.e. their crops
are generally preferred aesthetically)?
21 new subjects – ‘judges’ – rated sets of
cropped images produced by 6 croppers
from Study 1 who were chosen by cluster
analysis to have maximally disparate sets
of crops (A, B, C, D, E, F). On each trial,
a judge scored each of 6 randomly
arranged images (see figure 3b), rating
one image as ‘Best’ (4), two as ‘Good’
(3), two as ‘Bad’ (2) and 1 as ‘Worst’ (1).
Fig 3: a) croppings of image in Study 1;
b) crops by six croppers seen by judges
in Study 2
a)
b)
Crops made by some croppers (e.g. D &
F) were significantly preferred to those of
others (e.g. A & E) – see figure 4. We
conclude that some people consistently
produce more aesthetically satisfying
crops than do other people.
Fig 4: Preference of judges for crops by
six different croppers.
Five separate studies were carried out, with
a total of 71 subjects, 61 of whom were nonexperts, and 10 were taking the MA in
Photography at the Royal College of Art.
a)
b)
i.mcmanus@ucl.ac.uk
Study 3: This study replicated the
important conclusion of Study 2 with a
different set of 41 judges and a paired
comparison design. Cropper F was
significantly preferred to cropper B who in
turn was preferred to cropper E.
Study 4: What is the role of colour and
content in determining cropping?
Sixteen images were presented in colour, in
monochrome, and as ‘content-filtered’
versions (low-pass Gaussian filtered and
thresholded) which naïve viewers could no
longer recognise but retain the original
patterns of light and dark (see fig 5).
Subjects cropped all three versions of each
image, some thresholded versions being
presented first and others presented last.
Fig 5: Croppings of
colour, monochrome
and thresholded
versions of an image
There were few differences in median
cropping position between colour and
monochrome images, but large differences
between monochrome and thresholded
images. Within-image correlations were
high for colour-monochrome pairs, but
close to zero for monochrome-thresholded
pairs. We conclude colour has only a minor
influence on cropping position, whereas
content (meaning) has a large effect.
Study 5: Do expert photographers crop
differently from non-experts?
Fig 6: Cropping of image a) by 41 nonexperts and b) by 10 experts
a)
b)
Median horizontal crop positions were
similar for experts and non-experts, but
differed significantly in the vertical direction.
Experts also showed more variance in crop
positions, vertically and horizontally, took
longer to crop, and spent longer ‘dwelling’
on the image without moving the window.
Conclusions.
Photographic cropping is an ideal
experimental paradigm for aesthetics.
Subjects are familiar with the task, find it
natural, straightforward and interesting,
they differ in their choices of crop position,
and are consistent in their choices. Some
croppers are better than others, their crops
consistently being preferred to those of
other croppers. Cropping is influenced little
by colour, but much more by image content.
Experts crop somewhat differently,
particularly in the vertical direction, and they
show greater variability in their croppings.
A final important advantage, not always the
case in experimental aesthetics, is that
experts find the task interesting, appropriate
and natural, and are happy to carry it out.