classes, and are not sufficiently robust to be used in heterogeneous clinical environments.
[16]
1.4 Limitations of existing deep learning approaches
Deep learning and convolutional neural networks (CNNs), in particular, have significantly improved the medical
image analysis and dermoscopic lesion classification performance.
[17,18]
Traditional architectures like VGG,
ResNet, and Inception are highly accurate on hand-curated benchmark data.
[19]
Nonetheless, a number of
constraints exist when such models are implemented on realistic multi-class skin disease data that has a large
range of dermatological diseases. First, most of the previous studies are dealing with binary or low-cardinality
classification (e.g., melanoma vs. benign),
[20,21]
which are not representative of the entire range of dermatological
diagnoses seen in practice. The generalization of such models to multi-class problems in which dozens of types
of diseases are involved creates serious difficulties in learning the discriminatory features of visually similar
classes. Second, vanilla CNN architectures commonly assume that all spatial locations and feature channels are
equal, and there is no explicit representation of the relative significance of various regions and modalities of the
lesion image. The inability results in inefficient use of both local and global contextual information especially in
the presence of background artifacts (hair, rulers, markers or normal skin structures). Third, generic image
classification tasks are traditionally based on conventional deep networks, which are not optimized on a
systematic basis on depth, width, and resolution to the particular limitations of dermatological data. The risk
associated with over-parameterized model is that it overfits small or moderate size clinical data, whereas the
risk associated with under-parameterized architecture is that the model does not have enough capacity to learn
the more complex patterns of lesions. Moreover, most of the existing methods fail to solve specific domain-
related problems which include extreme imbalance of classes, uneven image quality and presence of non-
clinical artifacts within large repositories of skin images.
[22]
1.5 Need for robust automated multi-class classification
The above shortcomings encourage the emergence of effective automated classification schemes to suit the case
of multi-class skin disease detection in diverse image data. An effective CAD system in the field of dermatology
must meet a range of criteria: (1) high discriminative accuracy on a broad range of lesion types, including rare
but high-risk cases; (2) robustness to noise, changing illumination and acquisition artifacts; (3) effective
exploitation of labelled data through transfer learning with large natural image corpora; and (4) architectural
features to concentrate computational resources on areas of lesion of diagnostic interest as opposed to
unproductive background. In addition, these systems should be measured based on clinical priorities, such as
malignant and severe inflammatory or infectious disease sensitivity, and macro-averaged metrics, which
considers class imbalance. In multi-class scenarios, where further datasets such as DermNet-23, with over
twenty differing diagnostic cases, the heterogeneous visualization of the data has to be managed, yet not
favoring the majority classes. Such demands demand the high-level network designs involving the combination
of parameter-efficient backbones and explicit attention mechanisms as well as the strict optimization
techniques.
[23]
1.6 Problem statement
Nonetheless, even with much advancement in deep learning-based skin lesion analysis, some critical gaps are
found in research. To begin with, a comparative lack of approaches incorporating modern and compound-scale
architectures, including EfficientNet-B3,
[24]
alongside attention mechanisms with attention to dermatological
image properties, is relatively scarce. Most of the extant literature is based on the application of legacy CNN
backbones or the application of attention modules narrowly or in an ad-hoc fashion, without a thorough
examination of their effect on multi-class performance. Second, previous research tends to focus on the general
accuracy on a small sample of lesion types, without giving much indication of per-class accuracy and the model
behavior under strong imbalance between classes. Detailed studies based on macro-averaged precision, recall,
F1-score, and area under the ROC curve are required, especially when data includes different and uneven
diagnostic categories. Third, not many studies offer an end-to-end, reproducible pipeline to include effective
preprocessing, systematic data augmentation, optimized transfer learning, and attention-focused feature
refinement to large multi-class dermatology datasets. Lastly, it is not well-known how lightweight and attention-
enhanced architectures can help fill the gap between research prototypes and clinically viable CAD systems.
Namely, how the integration of parameter-efficient backbones and channelspatial attention will enhance
generalization without making the computationally unsustainable to be deployed in a real-world clinical setting
is not fully studied yet.
[25]
1.7 Novel contributions of this work
In order to fill the gaps, the work offers a transfer learning-based model of multi-classes of skin lesions
identification The summarized key contributions are as follows.
1. The paper uses an EfficientNet-B3 backbone as the main feature extractor of both dermoscopic and clinical