Definition

The intrinsic scale is determined by the highest resolution at which ​
​the image quality is excellent, and no annoying defects are visible.

Scale affects defect visibility

​Wrong focus, graininess, processing artefacts can detract from the appeal of an image.

​Viewing an image at a smaller size or scale factor, can make degradations less visible and annoying, improving the image's perceived quality.

Down-scaled version (20%) of an original photo. Its quality is high and no defects are visible. If this is the largest resolution at which this happens then it is the intrinsic image scale.

A crop from the original 6000x4000 px photo (100%). The image appears to be of low quality, blurry, and grainy.

Examples of quality defects

A high quality image (left) is degraded in several ways (right).

Defects reduce image clarity and fidelity

The example defects shown on the right are intentionally exaggerated to make them clearly visible. The intrinsic scale of the distorted images is very small in this case.

Finding the ​​intrinsic scale

In the following examples, each line shows crops taken from the same source image. Each crop is extracted after previously downscaling the source image by a different amount. You can often notice strong degradations at the original size (left-most), whereas the lowest resolution is of excellent quality (right-most image). The INTRINSIC scale is often somewhere in between.

​Note: it is best to view each image as is, do not click to enlarge.

    At the intrinsic scale:

• the image is of excellent quality
• it is well focused, clear and of high fidelity
• it is not showing any noise, artefacts, or other defects

slightly blurry

INTRINSIC

similar quality to the one on the left, but lower resolution

very blurry and grainy

still slightly out of focus

INTRINSIC

out of focus

slightly out of focus

INTRINSIC

slightly over-exposed

INTRINSIC

INTRINSIC

INTRINSIC

slightly blurry

INTRINSIC

INTRINSIC

INTRINSIC

over-sharpened

INTRINSIC

Participating in the experiment

You will annotate images using a browser-based interface, called Zovi. This allows browsing a collection of images, zooming to select the intrinsic scale for each, and saving the selection.

Zovi UI controls

Zoom: use the zoom slider at the top of the screen ​
Pan: click and drag the image​
Next image: press the green arrow buttons or the right arrow key.

Zovi annotation interface for selecting the intrinsic scale / zoom.

Steps to complete the work

1. Open Zovi in the Chrome web-browser
2. ​Select the intrinsic scale for each image
3. Move to the next image and repeat​
4. Submit your results at the end

2. ​Select the intrinsic scale

• explore the image to find any visible defects
• zoom out until the defects are not visible anymore
• repeat if necessary until no annoying defects are found​

I takes about 15 seconds to find the intrinsic scale (zoom) for each image. Thank you for participating in our study!