The Lasso is a fundamental selection tool found in Adobe Photoshop and many other image editing applications, used to draw freehand selections around specific areas of a digital image in order to isolate them for editing, retouching, moving, copying, cropping, or applying adjustments and effects independently of the rest of the image. By defining a selected area, the photographer or retoucher can confine any subsequent editing operations exclusively to the pixels within that selection, leaving the surrounding areas of the image unaffected.
In its basic freehand form, the Lasso tool allows the user to draw an irregular selection boundary of any shape by clicking and dragging the cursor around the area to be selected, following the contours of the subject as closely as required. When the cursor is released, the selection is automatically closed by a straight line connecting the start and end points of the drawn path, completing the selection boundary. This makes the basic Lasso well suited to making quick, rough selections of irregularly shaped areas where precise edge definition is not critical.
Most image editing applications offer additional variants of the Lasso tool to address different selection needs. The Polygonal Lasso tool creates selections by placing a series of straight line segments between anchor points clicked by the user, making it well suited to selecting subjects with straight or angular edges such as architectural elements, geometric shapes, and hard edged objects. The Magnetic Lasso tool is a more intelligent variant that attempts to detect and automatically snap to the edges and contours of a subject as the user traces around it, using contrast detection algorithms to identify boundaries between areas of differing tone or colour and anchor the selection path to them, making it particularly useful for isolating subjects against backgrounds with reasonable tonal contrast.
While the Lasso tool remains a versatile and widely used selection method in photographic retouching and compositing workflows, it has been supplemented in modern versions of Photoshop by more sophisticated selection tools such as the Quick Selection tool, the Object Selection tool, and AI powered Select Subject and Select and Mask features, which can produce accurate and detailed selections of complex subjects with considerably less manual effort than traditional lasso based selection methods.