Crop and Straighten

The Crop button in the Editor header opens a dedicated crop and straighten editor. It replaces the center canvas while active, and gives you handles, a rule-of-thirds grid, an aspect-ratio dropdown, and a straightening slider.

When to crop

The most common reasons to crop a stacked macro image:

Trim alignment edges. Stacking aligns frames by warping them into a common coordinate space. The edges often have a small black or transparent border from this warping. A crop reclaims a clean rectangle.
Improve composition. Tighten in on the subject, remove distracting edge elements, recompose to a different aspect.
Match output dimensions. Crop to 4:3 for a print, 1:1 for Instagram, 16:9 for a web header.

Cropping is non-destructive — you can re-open the crop editor and adjust at any time. The original full-resolution pixels are always preserved.

The crop rectangle

When you open the crop editor, you’ll see:

The image, fitted to the available space with letterbox padding around it.
A crop rectangle. On a result you haven’t cropped yet, it starts as a centred 4:5 rectangle inset a little from the edges — the Aspect dropdown starts on 4:5 and the rectangle follows it. If you’ve cropped this result before, your existing crop is restored instead. Either way, drag the handles out to the edges if you want the whole frame back.
8 draggable handles — 4 corners and 4 mid-edge handles.
A rule-of-thirds grid overlaid on the rectangle (visual guide; doesn’t snap).
The area outside the crop rectangle is dimmed so you can see what’ll be trimmed away.

Resizing the crop

Drag a corner handle — resize freely from that corner.
Drag a mid-edge handle — resize from that edge only.
Drag inside the crop rectangle — move the whole crop without changing its size.

If an aspect ratio is locked (see below), corner handles maintain the ratio; mid-edge handles still resize freely along their axis but the opposite axis follows.

Aspect ratio

The Aspect dropdown in the toolbar offers, in order:

Free — drag handles independently, no ratio lock.
Original — the image’s own aspect ratio, whatever it happens to be.
1:1 — square (Instagram, profile pictures).
4:5 — portrait. A good default for posting to social media.
5:4 — the landscape version of 4:5.
4:3 — Micro Four Thirds, many compact cameras, print-friendly.
3:2 — standard DSLR/mirrorless sensor ratio.
2:3 — the portrait version of 3:2.
16:9 — widescreen, web headers.

Changing the aspect locks the crop rectangle to that ratio immediately, snapping the current crop to fit. Choose Free again to release the lock.

The dropdown keeps whatever you last picked for the rest of the session — switch it to Free or Original and it’ll still be there the next time you open the crop editor, on this image or another one.

Straighten

The Straighten slider rotates the image by ±90°. The crop rectangle rotates with it (the image is what rotates inside the rectangle, not the rectangle), so the visible result is a rotated, cropped image.

The current rotation reads out as ±0.0° next to the slider.

Why the crop rectangle stops where it does

Rotating a rectangular image leaves empty triangular corners — the frame has to grow to hold the tilted picture, and the new corners have no pixels in them. So the crop rectangle is held inside the tilted image itself, not inside the larger frame around it. Push it past the tilted edge and it slides along that edge rather than crossing it; grow a corner handle into it and the handle stops there. Either way you can’t end up with black wedges in a saved image.

The edge it stops against is the diagonal one, so the further you straighten, the less room there is — at 45° a crop can only cover a fraction of the frame. At exactly ±90° nothing is lost at all: a quarter-turn is just the image on its side, so the crop can still cover the whole frame.

Zoom and pan inside the crop editor

The crop editor has its own zoom/pan controls separate from the main Editor canvas:

Scroll — zoom in/out (1.04× per scroll click — fine-grained).

⌘= / Ctrl+= — zoom in by 1.25×.
⌘- / Ctrl+- — zoom out by 1.25×.
⌘0 / Ctrl+0 — reset the zoom to fit.
Middle-click drag or left-click drag outside the crop rect — pan when zoomed in.
The cursor switches to a closed hand while panning.

Zoom is useful for precision crops near important edges — like cropping right up against an antenna or wing without clipping it.

Apply, Reset, Cancel

The toolbar at the bottom of the crop editor has three actions:

Reset — zero the Straighten slider and drop the rectangle back to the default position for whichever aspect is currently selected. Doesn’t apply or cancel.
Cancel — discard any changes you made in this session and return to the Editor with the previous crop intact.
Apply — commit the crop. The crop becomes part of the result; the Editor shows the cropped image; the history strip thumbnail updates.

Return / Enter applies the crop from the keyboard, and so does pressing R a second time (the same key that opened the editor).

If you click outside the editor by mistake, the crop stays open — nothing commits until you Apply.

Re-cropping later

The crop is non-destructive. To change the crop, click Crop again from the header toolbar (or press R) — you’ll re-enter the editor with the current crop selected, ready to adjust. To remove the crop entirely, set Aspect to Free, drag the handles out to the image edges, and Apply.

Tips

Straighten before fine-cropping. A 1° rotation changes the visible edges by a few pixels — straighten first so your final crop is tight.
Output dimensions follow the crop. If you crop a 6000×4000 image to 50% area, your saved TIFF/JPEG/DNG is half the linear dimensions. Crop with your output destination in mind.