Indian Journal of Dermatology
: 2022  |  Volume : 67  |  Issue : 5  |  Page : 547--551

Current status of using scale bar on clinical images and methods to insert it

Himel Mondal1, Shaikat Mondal2,  
1 Department of Physiology, All India Institute of Medical Sciences, Deoghar, Jharkhand, India
2 Department of Physiology, Raiganj Government Medical College and Hospital, West Bengal, India

Correspondence Address:
Himel Mondal
Department of Physiology, All India Institute of Medical Sciences, Deoghar, Jharkhand - 814 152


Clinical images are of utmost importance for the majority of dermatological research and publications. The rich collection of clinical images in medical journals may help in formulating machine learning programs in the future or facilitate image-based meta-analysis. However, the presence of a scale bar in those images is required for measuring the lesion from an image. We audited recent issues of three widely circulated Indian dermatology journals and found that among 345 clinical images, 2.61% had a scale with the unit. With this background, in this article, we provided three methods for capturing and processing clinical images with scale. This article would help dermatologists to think about incorporating a scale bar in the image for the progress of science.

How to cite this article:
Mondal H, Mondal S. Current status of using scale bar on clinical images and methods to insert it.Indian J Dermatol 2022;67:547-551

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Mondal H, Mondal S. Current status of using scale bar on clinical images and methods to insert it. Indian J Dermatol [serial online] 2022 [cited 2023 Mar 26 ];67:547-551
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Clinical imaging is an inseparable part of dermatological research and publication. For a clinician, it is important to keep the pre-treatment images to compare them with post-treatment images. It is also important for any future legal purposes. For an author, it is of utmost importance to capture and use the clinical images in a case report or other types of manuscripts.[1] For capturing images, the majority of clinicians use their smartphones as a replacement for digital cameras.[2] Although there are some limitations of the smartphone in producing a high-quality image for clinical usage, its proper use regarding the distance from the object, focusing on the object, appropriate lighting, optimum background, proper angle, and object stability can improve the quality of the photograph.[3]

If the gross clinical images do not have a scale with the picture, it becomes almost impossible to compare any lesion present on a clinical image with other images. For example, if a researcher wants to study and compare the size of lesions of ringworm found in different body sites or patients from different geographical areas, it would be impossible from the clinical images available online without a scale bar on the figure.[4]

In this article, we observed the presence and absence of scale bars in clinical images, review the problem faced due to the non-availability of scale bars, and discuss possible solutions. We presume that the scale bars in a clinical image would make them ready for any future artificial image analysis or image-based systemic reviews and meta-analysis.[5]

 Current Status

We browsed the current issues of three Indian dermatology journals—Indian Dermatology Online Journal (January–February 2022 issue), Indian Journal of Dermatology (November—December 2021 issue), and Indian Journal of Dermatology, Venereology, and Leprosy (January–February 2022 issue). Clinical images containing body parts, lesions, any specimen of interest, and magnified images from dermoscopy were included. As this study was concerned with clinical images only, microscopic images were excluded from the audit.

A total of 345 images were scanned and among them, 2.61% had a scale with unit marks and 2.61% of images had scale marks but without units. The presence of scales according to various article types is shown in [Table 1].{Table 1}

 The Problem

Dermatology being a visual subject, the author of the manuscripts is concerned about presenting the lesion. Many times, cropping an image or zooming in on an image is done for showing details about the lesion. However, when the scale information is not available with the image, it is difficult to appraise the actual size or compare the size with other similar lesions. This phenomenon is shown in [Figure 1] where an almost similar-sized red object is seen in three images. However, the actual size of the objects is shown in [Figure 2]. The red object size was biggest on the left hand and smallest on the middle hand.{Figure 1}{Figure 2}

 The Solution

Capture with a scale

Gross anatomical and pathological specimens are frequently captured with some scale with it. The same process may be followed for capturing clinical images with a scale. Hence, dermatologists may think about keeping a commonly available ruler with them. While capturing an image, one must help to hold the ruler or any other sort of scale. A cooperative patient can help hold the ruler when the dermatologist captures the image. Any physician's attendant can also help. However, the scale should ideally be placed on the same horizontal plane of the lesion to avoid any erroneous measurement. The error is depicted in [Figure 3]. In [Figure 3]a, one metal ruler was placed on the same plane of the lesion, and another plastic transparent ruler was placed on the flat surface on which the knee joint is resting. From image analysis, if the 1 mm distance of the lesion-level scale was taken as the reference, the 1 mm mark on the scale on the flat surface measures 0.59 mm, and it is due to the distance of the ruler from the lesion as shown in [Figure 3]b.{Figure 3}

Types of scales

Several types of scales can be used for clinical imaging. Three scales are shown in [Figure 4]. From left to right, a smartphone app-based scale, a plastic-made transparent ruler, and a piece of graph paper with millimeter marking.{Figure 4}

A scale with millimeter marking would be better as expressing the lesion in millimeters or centimeters is more common than inches. A metal ruler can be used where other scales are not available. However, it may reflect the light and cause glare in the image. It is to remember that metals may show higher values at a higher temperature. A fiberglass scale or scales made up of polyvinyl chloride plastic are devoid of this temperature-related change. Either metal or plastic-made scales can easily be disinfected with an alcohol swab after each use. For avoiding the problem of disinfection after each use, a disposable paper-made scale can be used. However, if it is not available, graph paper with millimeter marking may be the choice. A large sheet of graph paper can be cut into several pieces and stored for measurement. A piece of graph paper can be fixed near the lesion with the help of a surgical tape (e.g., Micropore™) and can be disposed of after capturing the photograph. If the graph paper is fixed near a skin lesion on a curved body surface, the paper may bend. This may give an erroneous measurement. In that case, the graph paper can be fixed to a disposable paper card for keeping it straight. Some smartphone applications can show a scale on the screen. This can be used in an emergency when other types of scales are not available. However, the scale should be checked for accuracy before using it.

Position of scale

A clinical image can be captured with the scale in situ. In that case, the scale should be placed just beside the lesion as unnecessary portions away from the lesion can be cropped off without affecting scale marking. However, in this article, we are describing two other methods of placing a scale bar in clinical images. In those cases, the scales can be placed away from the lesion. However, it is necessary to place the scale on the same plane of the lesion.

Presenting image with a scale

Method 1: Scale in image

This method is the most traditional way of capturing clinical images. A ruler or other available scale is placed near the object of interest. In [Figure 5]a, such an image is presented that was captured with a plastic transparent ruler near the lesion.{Figure 5}

Method 2: Scale sample in the image

In this method, the scale is placed away from the object and on the same plane of the lesion. The image is then edited in the Paint software (Windows image editing software bundled with the operating system). A sample of the scale is copied from the scale present on the image and it is placed near the object. The process in Paint is explained in Video 1[SUPPORTING:1]( A portion of the ruler is copied and pasted on the image, and it was dragged near the lesion. Care must be taken while dragging the scale image and placing it near the object so that the size of the image is not changed. After that, the unnecessary portion of the image along with the ruler was cropped off. A sample of such a figure is presented in [Figure 5]b.

Method 3: Scale bar in image

For inserting the scale bar, we describe the process in an open source software - ImageJ. Although it can be run on a browser, we used the downloaded software for the process. The software can be downloaded ( for any operating system (viz., Linux, Mac OS X, and Windows) as it is written in Java programing language.

The software is downloaded in a zip file. It should be unzipped before use. The unzipped folder contains a file with a microscope icon. Double-clicking on that file (with .exe extension) would open the application. The process of inserting a scale bar is shown in Video 2 ([SUPPORTING:2] The image of interest was opened in the application. Then, a line tool was taken to mark a known distance. A distance of 10 mm was marked on the graph paper. After that, it was set as a scale (Analyze – set scale) for further image analysis. Then, the scale bar was inserted (Analyze – Tools –Scale bar) in the right lower corner of the image. In the example shown in Video 2, we inserted a 10 mm scale bar. The bar can be inserted for other distances such as 20 mm and 25 mm according to convenience and size of the object. For example, in [Figure 5]c, the scale bar is 20 mm in length. The color of the scale should be such that it can easily be identified and measured in the future with similar software. We used a white bar with a black background for high contrast and ease of identification. It is also good for readers with color blindness.


The majority of the clinical images published with manuscripts in three Indian dermatology journals do not have a scale along with it. Hence, these images cannot be used further where measurements are required to find the conclusion. Some of the images were altered without maintaining the aspect ratio. For example, the faces were made taller to accommodate the image in a longer shape. This should be avoided and the ratio of the image should always be maintained while making it large or small. All images where we found scale marking without unit were from dermoscopy. Although the 10× magnification was mentioned, the scale marking without unit decreases the suitability for further analysis. Sometimes, the gross images are presented with a magnified lesion in the inset. The scale should be used for both images. During the image audit in this study, we found only one figure with a scale bar inserted with help of some software. The recent percentage of clinical images with a scale (2.61%) should be increased for making the clinical image ready for further analysis.

In this article, three methods of incorporating measurement scales in images were described according to difficulty. Those who are not very comfortable with editing images on a personal computer can keep the ruler near the lesion and capture the image and can present the image as such. In remote teledermatology facility centers where the diagnosis is based on still images, this method is the most suitable method as it does not need any editing.[6],[7] However, for presenting the image in the manuscript, method 2 and method 3 may be better suited. Those who have some experience in image editing can use method 2 where a small part of the scale is copied and pasted near the lesion and the rest of the scale is cropped off. This makes the image scientifically beautiful.

Those who have further interest can use the ImageJ software (i.e., method 3). It is an open-source software package and anyone can use it without any high-configuration computer. Insertion of the scale bar with contrast color would appraise the reader immediately about the scale. However, where the background should not be blocked due to some interest, the use of background can be skipped. In addition, the thickness of the scale bar can also be changed according to the necessity. We presume that readers would follow the videos, practice capturing and editing, and upgrade themselves with the simple steps described in the videos to jump from method 1 to method 2 or 3.

Whatever may be the method, a clinician needs a ruler or a measuring scale on any material to use at the time of capturing the image. In [Figure 3] and [Figure 4], four commonly available scales are shown. Students' ruler, either metallic or plastic-made is the most commonly available scale that can be used and reused with disinfection. Paper-based scales are good for single use to prevent any cross-infection. If the paper-made ruler is not available, it can be printed by the researcher by finding a suitable ruler from the Internet in portable document format. We found one such ruler at; we printed and checked it to be the same as an available plastic ruler. If this is not feasible, the next method is to keep graph paper in handy. As it is having millimeter marking, a piece of paper can be taken from the large sheet and used as the measuring scale.

There is some limitation of measurement from clinical images. One such limitation is that the three-dimensional body parts are presented in two-dimensional figures. If a lesion is present on the shin of the tibia and spread on both sides, then it would be difficult to measure the lesion from a picture taken from above the lesion. In that case, two other images are necessary from both sides to get the actual lesion size. As the distance between the camera lens and the scale is an important factor as shown in [Figure 3]b, the scale should be in each image on the plane of the lesion. Those who are using a digital camera for clinical photography may follow the tips shared by Kaliyadan et al.[8] and those who are using a smartphone may follow the guidelines by Ashique et al.[2],[9]


Clinical images published in recent issues of three Indian dermatology journals revealed that only a very few images are presented with scale. However, using a scale with the lesion may appraise the reader about the size of the lesion. In this article, three methods of presenting clinical images with a measurement scale are described. The easiest method is to keep a ruler near the lesion and present the image as such. The intermediate method is to take a sample (i.e., a unit) from the measuring scale and place it near the lesion and discard the unnecessary parts from the image. The third method encompasses capturing the image with a measuring scale and then the known distance is fed into the ImageJ software to insert a scale bar with the help of the software. Busy clinicians may choose from a wide range of scales such as plastic scale, paper-made scale, graph paper, or smartphone applications as per their convenience and present the image with scale for making it more suitable for ideation, comparison, and future analysis.

Participant consent

Written informed consent was obtained for adult research participants for using their images of skin lesions and normal body parts in this manuscript. For a toddler, written informed consent was obtained from the parents, and the assent was taken from the toddler for participation.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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