Reference image

The reference image feature lets you overlay an image on top of a pane, or show it and your site side-by-side. With this you can quickly compare a site to the design or to earlier screenshots to detect visual regressions.

If a reference image is shown, the icon will show a blue dot.

The reference image has two modes:

• Overlaid shows your site with the image overlaid on top of it. You can apply various filters, and fade between the image and the side. It also has a split view.
• Side-by-side shows your site and the image next to each other. This mode is only available in the horizontal and vertical layouts.

Read on for more info on the two modes.

Setup

Add a reference image by clicking the icon in a pane header.

Once you've selected an image, the pane will automatically resize to the width of the reference image.

From here, select if you want to show the image overlaid on the site, or side by side, and set an X and Y offset to position the image where you need it. the X and Y offset are number fields that you can increase with the arrow keys. Hold ⇧ while pressing the arrow keys to increase the offset by 10, and hold ⌘ while pressing the arrow keys to increase the offset by 100.

Removing the reference image

To quickly remove the reference image, click the icon in the pane header using your middle mouse button. Alternatively, click open the settings and click "reset".

Troubleshooting

The reference images is synced with the main scroller on the page, which you can find with document.scrollingElement. If your reference image doesn't scroll along with your page, then you probably have a different scrolling area overwriting that scrolling element (for example, a 100vh height div with overflow:auto as the top element)

The scrolling element is the designated scrolling element for the page (usually just the html element) and it's optimized compared to other scrollable elements, so it's the one you'll want to use!

Overlaid Image

With the image overlaid you can see both the image and the website, letting you easily see where the differences are.

Use the slider to fade between the site and the image, or toggle "Reference image visible" to quickly hide and show the image.

There are three overlay styles:

• Normal shows the image without any modifications
• Difference sets the "difference" blend mode between the image and the site. Everything that's similar turns black, and differences are highlighted.
• Invert Inverts the image. Everything that's similar turns grey. The differences from the image are shown inverted while the site retains its original colors.

Split View slider

The overlaid image has a slider on top of your pane so you can scrub between your site and the image. Useful for when you need to compare small details between the two.

Side-by-side image

This shows the image to the right of your pane, while syncing the scroll position so you can compare them side by side. You can disable the synced scrolling from the settings to scroll both individually.