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Image comparison at a glance

What the app measures, before you add anything.

9 comparison methods to pick from, Butteraugli by default
2 images per comparison, the reference and the one you check
7 image formats accepted, from JPG to TIFF
1 report you can export as a PDF, at no cost

Nine ways to compare images, not one

Compare images with the method that fits the question you are asking. The app offers 9 comparison algorithms, from perceptual measures that model how the eye reads a change to pixel measures that count every altered dot.

Butteraugli is the default. It estimates the difference the way a person would see it, so a change that catches the eye scores high and a change nobody would notice scores low.

The direction matters as much as the number. SSIM, NCC and PSNR say how alike the two images are, so a higher figure is a closer match. Butteraugli, LPIPS, AE, MAE and RMSE say how far apart they are, so a lower figure is the closer match. PDC simply counts the pixels that changed.

The method, the highlight colour and the threshold are set in the second step, before the comparison runs.

Find the difference between two images

Find the difference between two images and the app hands back a difference map: the second image with every changed area painted in the colour you chose. An object that was removed, a face that was edited, or a logo that moved shows up as a bright patch on an otherwise quiet frame.

There are 8 highlight colours: red, green, blue, yellow, orange, violet, black and white. Red is the default because it reads well on most photographs, but a red-heavy picture is easier to check in green.

For the pixel based methods, the threshold decides how large a change has to be before it counts, on a scale of 0 to 100. It starts at 4, which keeps faint compression noise out of the map while real edits still register.

LPIPS is the one method that returns a score without a difference map. The other 8 return both.

Read the image comparison report

Every comparison ends in one report. It opens with a similarity reading for the method you picked, then the difference map, then the numbers the reading was built from.

Methods that work per colour channel report red, green and blue on their own lines as well as a combined figure, so a colour cast shows up as the one channel that moved. The report also states what share of the total pixels differ.

File Details lines up the name, the size, the dimensions and the file type of both images side by side. That is usually where a resize or a second round of compression gives itself away before you have read a single score.

Export PDF saves the whole report as one file, free, with nothing to upgrade to first.

Which method should you compare images with

All 9 are free and all 9 run on the same two images. They differ in what the number means.

방식 What it measures Higher means more alike
Butteraugli Perceived visual difference 아니요
LPIPS Learned perceptual similarity 아니요
SSIM Structural similarity
AE Absolute pixel error 아니요
MAE Average pixel error 아니요
NCC Correlation of pixel values
PSNR Signal to noise ratio
RMSE Root mean squared error 아니요
PDC Count of differing pixels 아니요

Butteraugli, LPIPS and SSIM return a single fused score, so the colour threshold does not apply to them and the control stays hidden until you switch to one of the pixel based methods. LPIPS is also the only method that returns no difference map. Every other method returns a map and a set of per channel values alongside its score.

When an image comparison earns its keep

Three jobs where two versions of one picture arrive with no note about what changed.

Forensics and authenticity

Two copies of one photograph should match. When they do not, the difference map shows which part of the frame was touched and the score says how far it moved.

압축이 이미지 품질에 미치는 영향 확인

A smaller file always costs something. Compare the compressed copy against the original and the numbers say what the saving cost, instead of leaving it to the eye.

Design and review rounds

Two exports of one layout rarely differ where you expect. The map points at the pixels that moved, so a review takes a glance rather than a second pair of eyes.

Your images stay yours

The pictures people compare here are often evidence, unreleased work, or somebody else's face. Here is how they are handled.

Encrypted in transit

Both images travel over an encrypted connection. The link that brings the result back is generated at random, so it cannot be guessed by anyone who was not given it.

No human access

Nobody opens, reads or copies the images you compare, because the comparison is fully automated. They are never used to train AI models, and the copyright stays yours.

GDPR 준수

The servers that do the work are located exclusively in Europe, run by a named German controller, under a data processing agreement you can download.

이미지를 비교하는 방법

1

업로드

Add the first image. This is the reference the second one is measured against.

2

Add the second image

Add the image you want to check for changes.

3

Choose a method

비교 모델을 선택합니다.

4

비교

Start the comparison. Both images are checked and a similarity score comes back.

5

Review

두 이미지 간의 강조 표시된 차이점을 확인합니다.

Compare images FAQ

How can I compare two images?

Add the first image as the reference and the second as the one you want to check, pick a comparison method, and start the comparison. What comes back is a similarity score, a difference map with the changed areas marked in colour, and the numbers behind both. There is nothing to install and no account to open.

How do I find the difference between two images?

Add both images and read the difference map. It shows the second image with every changed area painted in the colour you chose, so a removed object, an edited detail, or a shifted logo is visible at a glance. The report also states what share of the pixels differ, which turns a hunch into a figure.

Can I compare two images for similarity?

Yes. Every comparison returns a score. SSIM, NCC and PSNR are similarity measures, so a higher number means the two images are more alike. Butteraugli, LPIPS, AE, MAE and RMSE are difference measures, so a lower number is the closer match. PDC reports a plain count of the pixels that changed.

Which method should I use to compare images?

Butteraugli is the default and it suits most pictures, because it estimates the difference the way a person would see it. Use SSIM when you want a structural similarity figure between 0 and 1. Use PDC when you want a count of the pixels that changed rather than a judgement about how they look.

Can I compare images that are different sizes?

The comparison lines the two images up pixel for pixel, so it works best when both share the same dimensions. There is no automatic alignment step. The File Details table reports the dimensions of both files, so a mismatch is easy to spot, and scaling the copy back to the original size before you compare gives the cleanest result.

Which image formats can I compare?

JPG, JPEG, PNG, WebP, GIF, BMP and TIFF. The two images do not have to share a format, so a PNG can be compared against a JPG of the same picture.

Can ChatGPT compare images?

An assistant can describe what it sees in two pictures, but it does not measure them, and asking twice can give you two answers. This app runs one of 9 named algorithms, returns a score you can repeat, marks every changed area on a map, and exports the result as a PDF you can hand to somebody else.

Is it free to compare images online?

Yes. Comparing images is free and no account is needed. Each image can be up to 75 MB, and a paid plan raises that to 8 GB.

The image comparison runs in the workspace

Add both images here and they open in the workspace, where the method is chosen and the report is built.

A two step upload

The reference image first, then the image you want to check. One step each, from your device, a link, or cloud storage.

Method, colour and threshold

Pick one of 9 algorithms, one of 8 highlight colours, and how large a change has to be before it counts.

The difference map

One picture with the changed areas painted in, next to the score, the per channel values, and the share of pixels that differ.

Export the report as a PDF

The score, the numbers and the file details of both images, saved as one file at no cost.

더 보기

Two photographs side by side with the changed areas outlined, illustrating an online image comparison
사용 방법

온라인에서 이미지를 비교하는 방법

A walkthrough of the 2 upload steps and how to read the score that comes back.

기사 읽기
A camera beside a photograph whose hidden shooting details are listed next to it
사용 방법

사진 메타데이터에 접근하고 관리하는 방법

사진가를 위한 가이드

기사 읽기
Two video frames stacked above a quality score chart, illustrating an online video comparison
사용 방법

온라인에서 동영상을 비교하는 방법

The same idea for moving pictures: frame by frame analysis and a quality score for 2 videos.

기사 읽기

Image metadata explained

A file icon opened to show the hidden data fields stored inside it
사용 방법

메타데이터란?

디지털 세계에서 메타데이터의 역할과 중요성 안내서

기사 읽기
A photograph beside a panel listing its camera, date, and location fields
사용 방법

온라인에서 메타데이터 보는 방법

Metadata2Go로 파일에 숨겨진 데이터를 확인하세요

기사 읽기