Inpainting vs Outpainting vs Generative Fill: The Difference

The one-line difference

Inpainting paints new content into a selected area inside the existing image — you mask a region and the model regenerates just that patch, blending it into everything around it. It is how you remove an object, swap a shirt, fix a blemish or replace a background without touching the rest of the frame.

Outpainting does the same trick pointed outward: it extends the picture beyond its original borders, inventing believable image where there was only empty canvas. It is how you turn a vertical phone photo into a wide banner, uncrop a subject that got cut off, or zoom out to reveal a scene that never existed.

Generative fill is the popular umbrella term — made mainstream by editing suites — for the modern, prompt-aware engine that powers both. When a tool lets you brush an area, type what should be there, and get a matched result, that is generative fill; whether it works inside or outside the frame is just which direction you dragged the selection.

What is inpainting?

Inpainting regenerates a masked region of an image while keeping everything outside the mask untouched. The model reads the surrounding pixels — the light direction, the perspective, the texture and grain — and synthesizes new content that continues them across the gap. Because it only rebuilds the area you marked, the rest of the photo stays pixel-identical, which is what makes an edit read as the original scene rather than a paste-up.

It is the most common AI photo edit, and it covers four jobs:

• Remove — erase a photobomber, a power line, a stray trash can, a logo, and let the model rebuild the background behind it.
• Replace — swap one object for another: change a shirt colour, put a different label on a bottle, retexture a wall.
• Repair — fix a scratch, a blemish, a sensor dust spot, or a torn corner on a scanned print.
• Add — paint a new element into an empty spot: a reflection, a shadow, an accessory the shot was missing.

What is outpainting?

Outpainting extends an image past its edges, generating new content that continues the existing scene outward. You place the original inside a larger canvas, mark the empty margin, and the model fills it so the seam disappears. The hard part is coherence — the new sky has to match the old sky, the extended floor has to keep the same perspective lines — and modern models are good at it precisely because they condition on the original edge pixels.

Reach for outpainting when you need to:

• Change the aspect ratio — turn a square or vertical shot into a wide 16:9 banner without cropping the subject.
• Uncrop — recover a head, a hand or a product edge that fell outside the original frame.
• Zoom out — reveal a wider environment around a tight shot, inventing the room, street or landscape that surrounds it.
• Fit a layout — extend a photo to bleed to the edges of a poster, ad or hero image at the exact dimensions you need.

Inpainting vs outpainting vs generative fill, side by side

The row that matters most is the last one: inpainting and outpainting are not competing tools you choose between — they are the same generative-fill capability, and most editors expose both from one brush. You decide which you are doing by where you draw the mask.

Masks: the thing that makes both work

A mask is the black-and-white map that tells the model which pixels to keep and which to regenerate — white for "repaint this", black for "leave it alone". Everything about the quality of a fill traces back to the mask. Too tight, and the model has no room to blend, so the object leaves a halo. Too loose, and it repaints good pixels you wanted to keep. The sweet spot is a mask that hugs the target with a little breathing room, and a feathered (softened) edge so the new content fades into the old instead of butting against a hard seam.

Prompt tips for a seamless fill

Inpainting and outpainting take prompts, and the prompt is not describing the whole image — it is describing what belongs in the mask. Follow this order for the cleanest result:

1. Describe the fill, not the photo. For a removal, prompt the background that should appear — "brick wall, even shade" — not the object you deleted. The model paints what you name into the gap.
2. Match the surroundings in words. Name the light, texture and perspective already in the shot — "soft overcast light, same wood grain" — so the new pixels join the old.
3. Keep the mask honest. Brush a little beyond the target and feather the edge; a margin of clean background is what lets the fill blend.
4. Lower the strength for repairs. A subtle fix (a blemish, a small extension) wants a gentler edit so it stays anchored to the original; a full replacement wants more freedom.
5. Iterate on the result, not from scratch. If the first pass leaves an edge, re-mask just that spot and run again on the same render rather than restarting the whole image.

A prompt for a fill is not a description of the picture — it is a description of the hole. Tell the model what belongs where the mask is, and match the light around it, and the seam disappears.

Which tools do inpainting and outpainting?

Three tiers of tool cover this. General image models — GPT Image and FLUX.2 among them — expose masked editing and can inpaint or outpaint from a prompt, giving you the most raw range. Editing suites popularized the generative-fill brush and bundle it with layers and manual retouching. And directed agents wrap the same models in a fixed brief so you skip the settings entirely — you brush, and the tool handles the mask feathering, the strength and the light-matching prompt for you. Which you want depends on how much control versus convenience the job needs.

Where ReelWand fits

ReelWand’s Object Eraser is inpainting with the controls pre-set: you brush over what should go, and it rebuilds the background behind it, matching the photo’s own lighting, perspective and grain — no strength slider, no feather setting, no prompt required. A server-side style DNA carries the "make the fill match the scene" instruction into every request, so a removed lamppost leaves the wall and sky, not a smeared patch. And because it iterates on the previous render, brushing again refines the same result instead of starting over — the difference between one clean pass and gambling on a fresh generation. For pure removals it is the fastest route; for prompt-driven replacement or outpainting, a general model gives you more reach.