Two exported product images can appear different simply because the review interface displays them differently. One may be fitted inside a square while the other fills a wide frame. Before deciding that an edit changed the product, make the comparison conditions explicit: display frame, fitting mode, background, and revision identifier.
Separate the review frame from the export
The review frame describes a display in your own interface. It does not prescribe the dimensions required by a storefront. Choose those requirements separately for the actual destination. A frame can help reviewers compare two revisions consistently, but it cannot prove that either revision meets the destination's upload rules.
Use the same fitting mode for both images. contain shows the whole image within the frame and may leave empty space. cover fills the frame and may crop the image. An edge that disappears under cover is not evidence that background removal erased it. Record the fitting mode with the review so that someone can reproduce what was seen.
Build a validated comparison record
This standalone JavaScript fixture creates a small comparison plan. The example chooses a 480 by 320 display frame only to make its behavior easy to test. Save it as comparison-plan.mjs, then run it with Node.js. The function does not load the images or decide whether an image is acceptable.
import assert from 'node:assert/strict';
export function comparisonPlan({ left, right, frame, fit, background }) {
const revision = /^[a-zA-Z0-9_-]{1,80}$/;
if (!revision.test(left ?? '') || !revision.test(right ?? '') || left === right) {
throw new Error('Two distinct revision identifiers are required.');
}
if (!frame || !Number.isSafeInteger(frame.width) ||
!Number.isSafeInteger(frame.height) || frame.width <= 0 || frame.height <= 0) {
throw new Error('Positive integer display dimensions are required.');
}
if (!['contain', 'cover'].includes(fit) || !/^#[a-fA-F0-9]{6}$/.test(background)) {
throw new Error('Unsupported review appearance.');
}
return { left, right, frame: { width: frame.width, height: frame.height },
fit, background };
}
const input = { left: 'mug_rev-a', right: 'mug_rev-b',
frame: { width: 480, height: 320 }, fit: 'contain', background: '#ffffff' };
const plan = comparisonPlan(input);
assert.equal(plan.fit, 'contain');
assert.deepEqual(plan.frame, { width: 480, height: 320 });
assert.throws(() => comparisonPlan({ ...input, right: input.left }), /distinct/);
assert.throws(() => comparisonPlan({ ...input,
frame: { width: 0, height: 320 } }), /Positive/);Apply the conditions consistently
In a browser review interface, give both image containers the recorded frame size and apply the same object-fit value. Keep the revision labels visible outside the image. Use descriptive alternative text for each view and ensure that a keyboard user can reach any zoom or revision-selection controls. Avoid conveying an acceptance decision through color alone.
After preparing a cutout with RemovePhotoBG, compare the export with its source under these recorded conditions. Then inspect the actual destination layout as a separate check. A consistent review display is a diagnostic aid, not a substitute for checking the final uploaded file.
Record what the comparison cannot show
A small display can hide edge halos and lost fine detail. Inspect a relevant area at native scale as well as the intended display size. Changing the background can reveal color contamination, while a close view can show jagged transitions. Those observations belong in the review note alongside the frame record. Keep the inspected revision immutable so that a later comparison does not silently point at a replacement file.
The MDN object-fit reference explains fitting behavior. Add interface tests that confirm both frames use the same plan, and use visual fixtures with a visible border to distinguish cropping from a genuine change to the export.