give an insight to the actual performance capability of traditional DL architectures; (c) it increases compu-
tational complexity without addressing the actual quality issue. To improve data quality, the optimal selection
of enhancement hyperparameters is extremely important. Due to the sensitive nature of medical data, this
selection is even more important to have a robust performance independent of the data quality. The exist-
ing methods rely on fixed enhancement hyperparameters. These hyperparameters are chosen according to
the dataset [Masud et al., 2021, Mittal et al., 2019, Hari et al., 2013]. Consequently, such enhancement meth-
ods are prone to overfitting. Moreover, these techniques are evaluated either on grayscale or RGB datasets
[Gao et al., 2021, Wang et al., 2019, Zhou et al., 2019]. Thus, this the limited evaluation is not indicative of
the strength of such methods. To prevent these issues, a computationally efficient and generalized contrast
enhancement method can help.
To overcome above stated issues, this paper proposes random data augmentation based computationally
efficient and generalized enhancement method, in which data quality is improved using random brightness and
contrast hyperparameters. Unlike other existing methods, which use fixed hyperparameters for enhancement,
we use a set of hyperparameters. The hyperparameters are randomly chosen from this set and hence are not
reliant on the dataset. The random selection ensures that the hyperparameters do not overfit the data. The data-
independent nature of these hyperparameters aids the proposed method to generalize well on different datasets.
The range of brightness set is [1.15, 1.35] and the range of contrast set is [−0.1, 0.4]. These specific ranges are
chosen by performing experimental evaluation. First we started from -1.0 for both hyperparameters, where
images have apparently no features. We evaluated the corresponding affect on enhancement by visualizing
resultant data and kept on incrementing the value with interval of 0.15. It was observed that images started to
show some feature at 1.15 and -0.1 brightness and contrast values respectively. Thus, these values were chosen
as starting points for contrast and brightness sets. For the end point, we followed the same methodology and
choose those values as end points before which images started to loose the features. The enhancement results
achieved with starting and end points of selected range are shown in Figure 4. Beyond this particular range,
image becomes darker or brighter and starts losing features. The performance is assessed by evaluating the
resultant enhanced data with a variety of traditional DL architectures.
Contributions: The main contributions of our work are as follows:
• We propose a generalized and computationally efficient random data augmentation based enhancement
approach for medical data.
• The enhancement hyperparameters are not manually selected according to the data; thus our enhancement
method does not overfit a specific dataset.
• To check the effectiveness of our work, we perform extensive experiments on both gray scale and RGB
datasets for classification and segmentation tasks.
• The proposed approach shows superior performance in terms of both accuracy and execution time over
state-of-the-art techniques.
2 Related Work
Generally three types of contrast enhancement methods have been used: histogram methods, spectral methods
and spatial methods [Pierre et al., 2017]. The histogram methods have remained very popular for contrast en-
hancement. Such methods transform gray scale images to an image with a specified histogram. However, such
methods result in poor enhancement that can be attributed to both loss of information and over-enhancement
of specific gray levels. Such methods are not adaptive and thus are inappropriate to provide contrast enhance-
ment for the medical imaging domain [Reddy et al., 2018, Singh et al., 2016]. Spectral methods use wavelet
transforms for quality enhancement. However, such methods fail to provide simultaneous enhancement to all
the parts of of images. Moreover, it is difficult to automate enhancement using them [Wang et al., 2019]. The
motive of the contrast enhancement in medical images is to aid clinicians with automated diagnosis, so such
methods are also not best suited for medical domain.