To crop one pixel layer while keeping your Affinity document the same size, make a rectangular pixel selection and apply it as a mask to that layer. This hides the unwanted area without deleting it. Export with Selection Only when you need that layer alone.

This guide covers the current Affinity desktop app on Mac, whose help uses Pixel Studio, Vector Studio, and Layout Studio terminology. The task is to restrict one layer’s visible content inside an existing composition, then optionally export it separately. The selection-and-mask workflow below follows Affinity’s documented Rectangular Marquee Tool and layer masking instructions.

Why does the Crop Tool crop the whole document?

Affinity’s regular Crop Tool operates on the canvas. Selecting a layer first does not turn it into a layer-only crop tool: the official help states that cropping affects the entire canvas and hides the regions outside the crop boundary. Its documented “crop an image to selection” procedure still uses that canvas operation. Cropping and straightening images

Three different boundaries matter here: the document canvas, the visible area of your pixel layer, and the area included in an exported file. Your intended result changes the second boundary while preserving the first. If you also need a separate asset, export settings control the third.

A mask provides that visible crop while retaining the original pixels. It does not promise to replace the underlying layer with a newly sized rectangular pixel buffer. Decide whether you need an editable crop in the composition or a separate output image before proceeding; those are related steps with different results.

How to crop only the selected pixel layer

Use this method when you already have a pixel layer and want to keep a rectangular portion of it. Affinity explicitly documents drawing a marquee on a pixel layer and using the selection for masking. Rectangular Marquee Tool

1. Select the layer and draw the area to keep

In Pixel Studio, select only the target pixel layer in the Layers panel. Choose the Rectangular Marquee Tool and set its selection mode to New, so an earlier selection does not get added to or subtracted from your rectangle. Set Feather to 0 for an unsoftened edge. For an opaque pixel edge, turn Antialias off; leaving it on smooths selection edges with partial transparency. Drag around the portion you want to retain. Rectangular Marquee Tool

The marquee identifies the keeper area. A pixel selection is a region for targeted editing and can serve as the starting point for a mask; drawing it alone does not crop the document or finish the layer edit. Affinity documents selections separately from canvas cropping. Creating pixel selections

2. Turn the selection into a mask

With the selection active and the target layer still selected, choose Pixel > New Mask Layer > Mask Layer. Affinity’s documented behavior is to hide the area outside the selection. By default, the new mask attaches to the selected layer; this behavior can be changed in Settings > Assistant, so check the Layers panel afterward. Layer masking

The visible result should be your chosen rectangle on that layer, with the surrounding composition still present. Check that the mask belongs to the intended layer rather than sitting independently above other layers: Affinity documents that an independent parent mask can affect layers below it. Layer masking

3. Check the result before exporting

Use three checks: the document dimensions should still match your starting document, an unrelated layer should remain visible outside the crop rectangle, and the target layer should show only the desired content. These checks distinguish a successful layer mask from an accidental canvas crop or a mask applied too broadly.

The hidden pixels remain available for revision. To check them, expand the layer and toggle the mask’s visibility. Affinity also documents editing a pixel mask with black to hide content and white to restore it. Layer masking

Can the Vector Crop Tool do this instead?

Affinity also has a Vector Crop Tool, available by default in Vector Studio and Layout Studio. Its documentation describes cropping a selected object or group, including images, by dragging inward from corner or edge handles. The tool has no default keyboard shortcut, so choose it explicitly. Vector Crop Tool

This tool creates a clipping mask on the object’s layer and preserves the original content. With Vector Crop active, dragging within the crop area repositions the object inside that boundary. It is a documented alternative for cropping objects within a composition. Cropping objects and groups

For the exact pixel-layer task here, the marquee-and-mask procedure is directly documented for pixel content. The Vector Crop help describes handle-based cropping; it does not document the regular Crop Tool’s numeric width, height, or resample controls for Vector Crop. Do not transfer those controls between tools or assume that a clipping crop permanently removes pixels. Vector Crop Tool, Cropping and straightening images

How to export the cropped layer without neighboring artwork

After masking, select the target layer in the Layers panel and choose File > Export > Export. Choose the required image preset, then set Area deliberately. Affinity distinguishes these options by both the selected layers and whether surrounding artwork is included. Export dialog

Area setting Documented output Use for this task
Whole document The current single-page document, or all artboards The complete composition
Selection Area The selection’s area, including overlapping deselected layers A region with surrounding artwork included
Selection Only The selection without overlapping deselected layers The selected cropped layer alone

These selection export options are available when one or more layers are selected. Export Settings

Here, “selection” refers to selected layers for the export contract. Do not rely on the marquee alone to exclude neighboring artwork. Re-select the intended layer, choose Selection Only, and inspect the preview. Affinity explicitly states that this setting excludes other layers overlapping the selection. Export dialog

Check the displayed output width and height before saving. Affinity allows alternative dimensions and provides Lock aspect ratio; these export controls resize the output image. They do not define a different keeper rectangle within your layer. If the composition needs a different crop, revise the mask first. Export Settings

For example, imagine a synthetic document containing a blue pixel graphic and a separate orange circle overlapping it. Mask the blue layer to the rectangle you want. Exporting Selection Area can include the orange circle; Selection Only, with just the blue layer selected, excludes that separate circle. This illustrative check follows the documented export distinction and helps catch an otherwise plausible-looking mistake. Export dialog

To finish, inspect the preview, choose Ask for Location, click Export, then name the file and choose its destination. Show in Finder is available if you want Affinity to reveal the saved output. Export dialog

What are the limits of this layer-only crop?

Masking preserves content. Both the pixel mask workflow and Vector Crop provide an editable visible boundary. If your requirement includes permanently removing stored pixels or guaranteeing smaller underlying layer bounds, a visual crop alone does not establish that result. Layer masking, Cropping objects and groups

Rasterize & Trim has a documented canvas boundary. Affinity offers Pixel > Rasterize > Rasterize & Trim, also available by Control-clicking a layer in the Layers panel. The help specifically states that partly off-canvas objects are trimmed and completely off-canvas objects are removed. It does not establish this command as a way to trim any pixel layer to an arbitrary marquee or mask rectangle. Do not use it as an assumed final step for this task. Rasterizing

Export size and crop size solve different problems. As an illustrative calculation, resizing an 800 × 600 output to 400 × 300 preserves its 4:3 proportions while halving each dimension. It does not choose a new 400 × 300 section of the original artwork. Affinity’s width, height, aspect-ratio lock, and resampling settings govern output sizing. Export Settings

Keep the editable document with its layer mask, and create a separate export when you need the cropped asset. The useful completion check is concrete: the document retains its original dimensions, only the intended layer is visually cropped, and the exported preview contains the content you meant to deliver.

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