## 1 Introduction
### Applications  
Malaria is a deadly disease that is considered endemic in many countries around the world [12]. In the year 2020, the World Health Organization (WHO) reported an estimated 229 million cases of malaria worldwide, which caused an estimated 409,000 deaths [13]. Malaria occurs in humans via protozoa within the blood cells of the genus Plasmodium. These parasites are transmitted by the bite of a female Anopheles mosquito [14]. The mosquito bite injects the Plasmodium into the affected person's blood, and then the Plasmodium parasites pass quickly to the liver to mature and replicate [15]. The most common imaging modality for detecting parasites in a thin blood smear sample is microscopical imaging [16]. While microscopy is relatively low-cost and widely accessible, diagnosis efficiency depends on the experience of parasitologists [17]. False-positive or false-negative diagnoses can lead to inappropriate or unnecessary prescriptions that can cause side effects in patients. Due to the global shortage of parasitologists in impoverished urban areas accurately processing the large number of specimens encountered is not always possible [18; 19]. Thus, CAD systems can be highly beneficial in this application.  
Another disease for which CAD systems can help by providing accurate early detection is diabetic retinopathy (DR). This condition is a typical development of diabetes, affecting the retina's small blood vessels, leading to vision deterioration [20]. The research described in [21] studies the offloading footwear to prevent and lower mortality rates in high-risk diabetic feet. A recent study has reported that DR affects the vision of 2.6 million people in the world [20; 22]. Several retinal imaging systems can be utilized to detect the indication of diabetic retinopathy, including color fundus photography, fluorescein angiography, B-scan ultrasonography, and optical coherence tomography [23]. The retina images that we use in our study have been captured using fundus photography under a variety of imaging conditions. Early-stage diagnosis of DR grading is integral to prevent the occurrence of blindness. Hence, CAD systems could help save millions of people from potentially preventable vision loss and blindness by improving early detection.  
The third and final application we consider here is pulmonary tuberculosis (TB). This disease is a significant public health issue causing more than 9 million expected new cases and roughly 1.4 million deaths every year [24]. The detection of TB on chest radiographs (CRs) is essential for diagnosing TB. Chest radiography imaging (e.g., X-ray or computed tomography (CT) imaging) is easy to perform with fast diagnosis and has a high sensitivity for diagnosing TB infection. However, CRs are the fastest and most affordable form of imaging and require significantly less radiation, data memory, and processing time than CT scans [25]. The WHO recommends using CRs to screen and triage people for TB [26]. Note that CRs are among the first procedures of examination related to suspects' lung disease. They are low-cost and widely accessible for health care providers. The use of CAD systems for TB detection can help radiologist workflow so they may be able to process more cases with greater accuracy.