Hacker News Reader

Comment by tudorconstantin | Hacker News Reader

What a great idea. I am renovating my house right now and I have to buy some paint for partially painting a facade. I could use such an app to be able to choose the paint color, in the store, as close as possible to the original one.

Do you know of any such app for Android?

View on HN

Beware the effects of incident lighting on colour perception. As a human, you do a lot of processing you're not even aware of to normalise the colours you perceive. Cameras cannot do this (without calibration), so if the incandescent/flourescent/daylight/sunlight mix and intensity is different in the store to your house, you could end up with a very different shade.

It's really interesting. My wife and I have done lots of painting at our house over the past year and we never get exactly what we expected. Most recently, we spent a long time selecting a light gray, which looked very much gray with a group of other grays. Then we painted the first portion of wall, stepped back and both said, "well, that is blue".

I'm guessing you looked at the paint in the shop under artificial lighting (which is more orange - making blues look more grey), then painted it in your house where there is more bluer daylight!

Always buy the extortionately priced test samples. It's worth it!

Matching the appearance of existing paint / colored surfaces is difficult.

You need data on the variation of colour, intensity and reflectance as a function of viewing and illumination angles. Not something a mobile device can do.

The device described in this paper can: (note: I am not affiliated; just out of interest)

http://www.pro-lite.co.uk/File/RAD%20Imaging%20Sphere%20Pape...

[Edit: spelling]

If you have an app, and a standard color card[1]. then the processing to normalise the image (and therefore the colours) should be doable on a mobile device.

[1] https://www.amazon.co.uk/gp/product/B004QXU8VI/

To convince yourself of this, just google "optical illusion color".

If you really care about matching existing paint, you want specialized equipment. Professional colorimeters call handle this task with ease, but I don't think smartphone cameras are quite up to the task.

If I wanted to do this, I'd try something like the Color Muse [1]. It's a $60 Bluetooth peripheral that proports to do accurate color scanning. Then an app on your phone tells you the specific paint that corosponds to the scanned color.

I haven't used it personally and can't vouch for it's performance, but I wouldn't trust phone camera alone and wouldn't spend $1k+ on a pro model, so I figure it's worth a shot

[1] https://www.amazon.com/dp/B01KKEMIF0/

Well, I made this one back in 2011. But please don't use it for selecting paint. https://play.google.com/store/apps/details?id=com.jenspeterv...

Lots of DIY stores will custom-mix colour matched paint if you take a chip of it in.

Reply on news.ycombinator.com