Why the iOS folders are rounded on 3×3px wallpaper?

This post is in English. Usually in Japanese.

今回は全文英語。フォルダが丸くなる壁紙を中心に、これまで当ブログで分析してきたiOSの壁紙仕様をかいつまんで述べています。

Why iOS 9.3 folders are rounded on 3×3 without Jailbreaking?  (Why folders are colored?)

▶︎ Round Folders

Of course I don't know. But I have a key to the mystery.

Take some time. It's necessary to order.

iOS Dock and folders are picking up neighbor colors.

iOS 8.0 or later, If we set the image smaller than standard. Colors are picked up more! 

The same as it is image is smaller to expand the wallpaper

The smaller, the more strong.

If enough small (45px width wallpaper, etc.), Dock and folders are colored perfectly (For some reason, the margin is more influence.). 

The size makes the round folder some place, some device on iOS 9.3! (3×3 is the best for iPhone 6 Plus Standard View–Zoomed View average. Plus might be most hard.)

If the stain is halved (90px width, etc.) or colorless (1px width), folders are not rounded.

Even 3×3, Reduce Transparency switched On, folders are repaired. 

Left: Normal setting Right: Reduce Transparency

With Reduce Transparency, Dock and folders don't pick up any color.

These findings make me think that the trigger of the glitch is not "image size". It should be the bug funny folders shape by the amount pick up the color from background. (On iOS 10, the threshold is changed. It is more instability than iOS 9.3.)

Why Round Folders is not darkened on iOS (8.3-9.3) Home Screen?

Round Folders is not darkened using any colors.

Round Folders Bright

Usually, vivid wallpapers are darkened on iOS. Why? For letters visibility?

A darkened Home Screen

Home Screen doesn't turn dark on bright enough or sufficiently dark wallpaper.

Upper: bright enough Lower: sufficiently dark

iOS 8.3 or later it is related with the size of the color and brightness determination. The smaller, the darker.

For more information Look at the figure below.

Tap to display the original image
This is not official, is due to my experiment and observation

That is the reason for 3×3 is sufficiently small!

The other wallpapers using these tips

Colored Dock and folders. One of them is never darkened. (Folders are rounded in same cases.)

▶︎ Color UI Wallpapers

Full white with a controlled brightness by the size.

▶︎ FFFFFF (All F) iOS8.3-9.3

Never darkened! ​Screen size independent! (Folders are rounded in same cases.)

▶︎ Freedom iOS 8.3-9.3

Never darkened PANTONE® color wallpapers.

▶︎ Color Trends for iOS

Have a nice screen!

So, moving still images without 3D Touch. Micro pattern raises the moire on perspective.

These are actual screenshot!

▶︎ Static Dynamic Wallpapers

The pale colors, brightness limit for keeping the tone. It's makes invisible Dock and folders.

▶︎ Seamless Wallpapers iOS 8.3-9.3

▶︎ Hide Dock Wallpapers

I'm afraid my expressions are hard to read. I'm not so good at English. I combine translator app, English checker app, search and my feeling. Please be patient!