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How Dermi Atlas builds comparison groups from a clinical entry and presents them in split and overlay views, with layouts, layer opacity, manual registration, undo, and Quick Export.
A comparison group is a set of a patient's images held together so they can be viewed as one subject rather than opened one at a time. Dermi Atlas builds the group from the images already gathered in a clinical entry workspace and opens it in a full-screen workspace with two surfaces: a split view that places the images in adjacent panes, and an overlay view that stacks them as layers with adjustable opacity. Clinicians use the two together to read change across a treatment arc, once from the arrangement and once from the blend.
This article covers creating a comparison from an entry, the split layouts, the View, Arrange, and Annotate modes, overlay opacity and layer visibility, manual registration, comparisons that span several magnifications, undo and redo, what is saved with a comparison, and Quick Export.
Comparisons are built in the entry workspace, where the images documented for a visit are already assembled. Selecting the checkbox on a workspace image raises a floating selection bar carrying the running count, a control to clear the selection, and Create Comparison. Fewer than two images leaves the action disabled with the hint "Select at least 2 images".
Create Comparison assembles the group from the selection and sorts its images chronologically by effective date, so the panes and layers open in visit order regardless of the order the images were picked in. A selection matching a group that already exists is declined with a "Duplicate comparison group" notification rather than creating a second copy of it.
Illustrative demo with synthetic data. Learn more
The finished group appears as a card in the Comparisons section of the entry, showing a thumbnail collage, the date range the images span, the image count, a badge for any comparison marks on the group, and a Caption field. The card carries Compare Images, which opens the comparison workspace, and Remove Comparison Group. A counter above the section reports how many comparisons the entry holds, and a header control shows or hides annotation overlays on the thumbnails.
Opening a group replaces the page with a full-screen workspace. Its header carries the Split and Overlay tabs, the surface controls for the open tab, a save and presence indicator, and the control that opens Rendering Settings, the page holding the canvas quality options (supersampling, image smoothing, and the resolution bounds applied during and after interaction). A comparison opens on the Split tab.
The commands for the open surface sit in a toolbar along the bottom of the canvas: the mode selector, Undo and Redo, the split-layout control on the split surface, annotation layer visibility, the positioning commands, and a terminal zoom chip. On narrow widths the lower-priority items collapse into a More Options menu grouped by section.
The mode selector governs what a gesture on the canvas does, and the three modes are mutually exclusive.
Escape returns the canvas to View.
The split view divides the canvas into one section per image and fits each image into its own section. Three layouts are offered from a segmented control, and each switch animates the images into their new sections:
Illustrative demo with synthetic data. Learn more
A caption pill at the top of each section carries that image's date, controls to swap the image left or right within the arrangement, and the anchor that sets it as the alignment reference. The Captions control in the header shows or hides the whole caption overlay.
The zoom chip in the toolbar reports the current magnification and opens a slider with preset levels beneath it. In View mode the zoom applies to every section about its own center and a drag pans all of the images together, so the same anatomical detail is magnified and framed identically in each pane.
Illustrative demo with synthetic data. Learn more
The Overlay tab stacks the same images on one canvas, newest on top, and pairs the canvas with a layers panel. The panel is docked beside the canvas on wide screens and opens as a drawer from the Layers control on narrower ones.
Each layer is represented by a card holding its thumbnail, its date, the count of any marks on it, the anchor that sets it as the alignment reference, a grip handle for reordering the stack, an eye toggle, and an opacity slider.
Lowering the opacity of an upper layer lets the layers beneath it show through, which is how the overlay is read: at a partial opacity two visits occupy the same pixels and the difference between them reads directly rather than across a gap.
Illustrative demo with synthetic data. Learn more
The eye toggle hides a layer outright, which steps the visible stack back to an earlier visit without disturbing the arrangement. A hidden layer keeps its position, its opacity, and its marks, and the same control restores it.
Illustrative demo with synthetic data. Learn more
The zoom chip behaves differently here than in the split view: it magnifies the canvas viewport about its center, so the whole stack scales together and stays registered while it grows.
Auto Align Images, in the Arrange toolbar, registers the images automatically by locating and pairing visual features between them and computing a transform for each image relative to the chosen reference. The full behavior, its inputs, and its limits are covered in Automatic Alignment for Image Comparisons.
Registration can also be adjusted by hand. In Arrange mode a drag on the canvas moves a single image: one pane's image in the split view, or the selected layer in the overlay. Small nudges of this kind refine a registration that is close but not exact, and each nudge is a separate step in the comparison history, so it is reversible.
Illustrative demo with synthetic data. Learn more
Further commands sit beside the align control in Arrange. Reset Transforms returns every image in the comparison to its original position, clearing manual adjustments and computed alignment alike. Center Images recenters the images and adjusts their scale without discarding the rest of the arrangement. The overlay adds Reset All, which resets the transforms and the view in one step.
A comparison group is not restricted to images photographed at a single working distance. An overview frame, a close-up, and a macro frame of the same site can be grouped together and, within the accepted alignment range (up to roughly a four-fold scale difference), aligned so that the shared anatomy occupies the same relative position in each section, then inspected in one pass: because the panes move and magnify in lockstep, the same site stays in frame at every scale while the finest section supplies the detail.
Illustrative demo with synthetic data. Learn more
This matters when imaging protocols differ between appointments or when a lesion is documented both in context and up close. The registration behind it is described in the automatic alignment article.
Each comparison surface keeps its own history for the length of the session. Undo and Redo sit next to the mode selector in the toolbar and are also bound to the standard shortcuts: Command or Control with Z to undo, adding Shift to redo, and Command or Control with Y as a second redo binding.
The history records the actions that change the comparison rather than every intermediate frame. Moving, scaling, or rotating an image, changing the layout, running Auto Align, setting the alignment reference, toggling a layer, reordering the stack, changing a layer's opacity, and each of the reset commands all enter as their own step; a continuous opacity drag is collapsed into a single entry so one sweep is undone in one step, as is a continuous zoom in the split view, while overlay camera moves are not recorded as steps and are absorbed into the next undo instead. Up to 30 steps are held per surface, and the history is session-scoped: it is not written to the record and does not survive a page reload.
A comparison is a persistent part of the entry, not a transient view. The images in the group, their order, the caption, the split arrangement and its layout, the overlay arrangement, the layer opacities and visibility, the alignment reference, the computed alignment, and any comparison marks are all stored with the group.
The arrangement is committed once the workspace is closed. Reopening the group restores it exactly as it was left, which is what makes a comparison worth building for a lesion that will be revisited at every appointment: subsequent visits are added to a workspace whose framing is already established.
Quick Export, in the terminal section of the toolbar More Options menu, writes the comparison as it currently stands on screen to a JPEG file in one step. The live arrangement is reproduced faithfully, then fitted and centered on a standard square frame with white bands filling the remaining axis, and exact dates are stamped on the frame. The Dermi Atlas badge follows the remembered export preference; no practice logo is drawn. The file is named for the surface, the group, and the moment of export.
The export is recorded automatically with the clinical documentation purpose and the media consent status of the patient at that moment, so nothing is asked at the point of export. The configurable path sits directly above it: Export Options opens the full export drawer, with frame presets, date and label options, branding, and output sizes, described in Exporting Images with Custom Export.
The two surfaces answer different questions. The split view holds several visits apart from one another, which suits a conversation with a patient and any reading where the individual frames must stay legible. The overlay puts them in the same coordinates, which suits a close inspection of a single site where the difference between two dates is small enough that a gap between panes would hide it. Because both surfaces belong to one group and share its alignment, moving between them costs nothing.
Building a comparison once and returning to it is what turns a folder of visit photographs into a longitudinal record. The arrangement, the registration, and the marks are kept with the entry, so the same framing is available at the next appointment and the clinician compares like with like rather than rebuilding the view from memory.
Every feature described here is available in Dermi Atlas Professional, the on-premises deployment designed for clinical use. The Dermi Atlas Cloud Demo provides access to core workflows for evaluation, though some capabilities may be restricted.
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All demonstrations, screenshots, and media on this page use synthetic data only. No real patient information is shown.
The following are synthetic and do not correspond to real patients:
Media is provided solely to illustrate platform functionality and workflows.