Detecting an accessory

An image-forming device comprising:

• a controller;
• a print platen suitable for receiving a substrate;
• and
• a handling mechanism to maneuver a substrate received on the print platen;
• wherein the print platen comprises an optical sensor to capture at least a pair of images of an item received on the print platen;
• and further wherein the controller is to:
• trigger the capture of the at least the pair of images;
• trigger an adjustment action, by the handling mechanism, to adjust a position of the substrate on the print platen;
• and
• identify the presence of a demountable accessory based on an identified accessory identifier in the captured at least the pair of images.

A non-transitory machine-readable storage medium encoded with instructions executable by a controller that when executed cause the controller to:

• capture, using an optical sensor associated with a print platen in an image-forming device, a first image of an item on the print platen;
• carry out an adjustment action, using a handling mechanism of the image-forming device, wherein the adjustment action is to adjust a position of a substrate on the print platen;
• capture a second image using the optical sensor;
• analyze the first image and the second image to identify displacement;
• analyze at least one of the first image and the second image to detect an accessory identifier;
• process the results of the analysis to determine the presence of an accessory on the print platen and to classify the accessory based on the detected accessory identifier.