EV3: `brightness` block measures by blue light, not by red light

[nekketsuuu]

Expected Behavior

When using brightness block, the color sensor measures it by red light.
The official page 45506 EV3 Color Sensor also says that

Measures reflected red light and ambient light, from darkness to very bright sunlight

Actual Behavior

brightness block measures it by blue light.

Also the measured value is low. In my environment, it's between 1 and 26 when using brightness block, although the port view of EV3 says it's between 0 and 97 percent when using COL-REFLECT mode ^{This is because the block measures brightness using the ambient mode. If I use the port view with COL-AMBIENT, the measured value is 0-26. See my comment below.}

Steps to Reproduce

1. Connect one color sensor to a EV3.
2. Connect the EV3 to a computer using Bluetooth and Scratch Link on https://beta.scratch.mit.edu/.
3. Try to measure reflection using brightness block.

Operating System and Browser

Windows 10 Home 1803, Google Chrome 68.0.3440.106 (Official build) (64 bit), 45506 EV3 Color Sensor
I tested on https://beta.scratch.mit.edu/, on Aug 12, 2018.

[nekketsuuu]

I found that the extension measures brightness using the ambient mode (in this line). Therefore EV3 uses blue light to measure. Is there any reasons to use the ambient mode (by blue light), not the reflect mode (by red light)? Personally I use the ambient mode not so much.

[thisandagain]

/cc @ericrosenbaum @evhan55

[evhan55]

@nekketsuuu Thank you for the question, we will check it out!