TABLE 1.

Definitions of twenty image utilization technique features occurring in included skin imaging applications

Category	#	Feature	Definition	Example
Metadata	1	Free text/structured fields	Option to provide additional information about an image prior to submission, either through free text fields or writing in/selecting options in structured fields	Free text: After uploading an image of their skin, the user can write in additional comments in a free text box prior to submission. Structured fields: User is asked to answer pre‐written, multiple‐choice questions about the duration, morphology, and evolution of their skin lesion prior to image submission.
	2	Timestamp/temporal labeling	Automatic labeling and/or sorting of images by the date and time uploaded or submitted	When navigating to previously uploaded images, the user sees them arranged in date‐time order with grey timestamps beneath each thumbnail.
	3	2D body map tracking	Ability to identify anatomic location of skin complaint in two‐dimensional space, usually on an avatar	After taking an image of their skin, the user sees a 2D anatomical model and is asked to tap the location closest to that of the real‐life skin lesion.
	4	Image/album labeling	Ability to retitle images or groups of images organized into folders/albums	User selects 3 photos out of the 15 that they have uploaded and moves them to a new in‐app folder, which they title “Rash R Arm March 2020.”
	5	Lesion measurement	Automated (in‐camera or device‐based measurement scale/frame) or guided (with reference object or user‐based estimate) measurement of lesion size	User is instructed to include and identify a reference object (quarter) in their skin image. After the image is uploaded, “2 × 3mm” appears automatically in the size field.
	6	3D body map tracking	Ability to identify anatomic location of skin complaint in three‐dimensional space, usually on an avatar	After taking an image of their skin, the user sees a 3D anatomical model and is asked to rotate, zoom, and then tap on the location closest to that of the real‐life skin lesion.
Functional tools	7	AI diagnostic analysis	Application returns some type of diagnostic output with respect to an uploaded image; outputs can be binary, risk class‐based, a list of ranked or unranked diagnoses, and/or a score on a continuous risk scale	After submitting an image to the “AI Analyzer,” the user sees results suggesting that their lesion has a 57.1% chance of malignancy and that they should contact a dermatologist.
	8	Digital share	Ability to share labeled images/image albums, lesion analyses, symptom visualizations, or other in‐app media via email or through other smartphone apps (i.e., text messaging)	When viewing a graph tracking the severity of itch associated with uploaded images over time, the user sees a “Share” button that automatically attaches the PDF to a new email.
	9	Photo reminders	Ability to set and/or customize in‐app reminders to take skin images	A psoriasis patient receives weekly reminders every Saturday to take and upload images of their affected skin.
	10	Compare lesions	Ability to see two or more skin images side by side	After selecting two previously uploaded images and clicking “Compare,” the user sees one on the left side of the screen and the other on the right.
	11	In‐app zoom	Ability to zoom in on or magnify any area of an uploaded image	User selects a photo and pinches in with two fingers to get a magnified view of any area.
	12	File format conversion	In‐app conversion of uploaded skin images between different file types	After uploading a DICOM file to the app interface, the user can choose to download it as a JPG, PNG, or TIFF from within the same application.
Image processing	13	Image cropping	Removal of unwanted outer areas from uploaded skin image	After uploading an image, the user trims/removes outer areas representing extraneous background by moving the image borders closer together.
	14	Magnification to resize	Ability to resave a magnified/zoomed in version of a previously uploaded image	After uploading an image, the user pinches in with two fingers to magnify the lesion of concern and saves the magnified version of the image.
	15	Image realignment/orientation	Ability to rotate a previously uploaded image, most commonly to reorient it with a previous image or to facilitate ease of interpretation	After uploading an image, the user hits an arrow button to rotate the image 90°.
	16	Color/contrast correction	Automated or manual ability to adjust color contrast, saturation, filters, and so on, usually with the goal of more accurately representing real‐life appearance	After noticing that their uploaded photo has an orange cast due to harsh lighting, the user adjusts the image contrast and yellow/orange tones using an in‐app color filter.
	17	Image markup	Ability to add text boxes, digital pen markings, or other artificial elements to the image	After uploading an image, the user adds an arrow pointing to the lesion of interest.
	18	Light balance correction	Automated or manual ability to adjust light balance, usually with the goal of more accurately representing real‐life appearance	After taking an image in a shadowy room, the user uses the light adjustment feature to “brighten” the image so that the lesion of interest is more visible.
	19	Obscuration removal	Automated or manual removal of anything covering the lesion/area of interest	After noticing that their bracelet partially obscures their rash in a previously uploaded skin image, the user presses “Remove Obscuration” to replace it with a skin‐colored area.
	20	Background removal	Automated or manual removal of extraneous, non‐skin image background	After noticing a brightly colored shirt in the background of a previously uploaded skin image, the user presses “Remove Background” to replace all non‐skin background with solid grey.