Contents
Comparing images
With images, a line comparison is useless. MergeQaiPro therefore contrasts them as images — in four display modes, with zoom, coupled panning and a rating of how similar they really are.
9.1 The four display modes
| Mode | Shows | Own slider |
|---|---|---|
| Side by side | both images separately | — |
| Overlay | the right image on top of the left | Opacity |
| Slider | vertical dividing line: the left image on the left, the right one on the right | Position — the handle in the middle of the image can also be dragged directly |
| Difference | amplified pixel difference: black = equal, bright areas = deviation | Amplification |
9.2 Tools
| Tool | Function |
|---|---|
| ⇄ Sync | zoom and panning of both sides coupled. To pan: grab the image with the left mouse button and drag |
| Blink | alternates continuously between the two images — makes the smallest differences visible as movement |
| Grid | shows a rule-of-thirds grid |
| Fit · 100 % | fit the image or show it at original size; the mouse wheel zooms at the point under the pointer |
The magnification you set is kept when you switch the display type. If you have zoomed in on a spot at 400 %, take a quick look at Text or Binary and come back, you will find the same view — after all it is still the same comparison, only the way of looking at it changes. Only when you open a new comparison, or pick different files, is the image fitted again.
9.3 How similar are the images?
Above the images stands a similarity in per cent. It is not a mere pixel comparison but is composed of five measurements — the tooltip breaks it down:
- Perception (DCT) — how similar the images look to the eye
- Structure — composition and edges
- Brightness
- Colour distribution
- Aspect ratio
Next to it stand the hard numbers: the dimensions of both images (“Left 1920×1080 · Right 1920×1080”) and how many pixels deviate (“99.4 % equal · 12,480 deviating pixels”). If the images are identical, MergeQaiPro reports “Images are identical”; with differing dimensions, “Different dimensions”.
9.4 Tidying up directly
Once you have decided which image should stay, you can do it right here: ⇒ To the right and ⇐ To the left copy one file over the other, 🗑 Delete left and 🗑 Delete right remove one of them.
