poshwal

Automatically generates and applies themes for Windows terminals (both classic conhost.exe and the new Terminal) based on the colors found in an image.

Although the name is a reference to pywal and this script is supposed to provide a similar feature for the Windows platform it borrows no code or algorithms from pywal - I wanted to learn and create something of my own (this is also a good excuse for why it's not perfect I guess).

Syntax

./poshwal.ps1
    [[-ImageFile] <String>]
    [-Apply]
    [-LightTheme]
    [-MapColorsByHue]
    [-SetWallpaper {Fill | Fit | Stretch | Center | Tile | Span}]
    [-SimilarColorThreshold <float>]
    [-SimilarColorAlgorithm { RGBTotalAverage | RGBIndividual }]
    [-RequiredBrightnessDifference <float>]
    [-NotEnoughColors { Extrapolate | Reuse }]
    [<CommonParameters>]

Usage

Download the latest release from here and run:

Simplest example:

./poshwal.ps1 -Apply

The script also accepts an image file over the pipeline:

ls "$env:USERPROFILE\Pictures" -Filter "*.jpg" | Get-Random | ./poshwal.ps1 -Apply -SetWallpaper 'Fill'

If you wish to see more details on how a theme was decided on to tweak parameters for future runs, looking at the -Verbose output will be necessary:

./poshwal.ps1 -ImageFile "\\nas\Share\example.png" -Verbose

By default the script will try to match colors from the image to their most appropriate spot in the theme so that output from commands like Write-Host "Success" -ForegroundColor Green is still somewhat green and even generate colors not actually in the image if nothing close at all was found. This is a safe default because it ensures any console apps you have that rely on colored output to convey information will work.

However, if you do not want colors generated but strictly use what's in the image you can run:

./poshwal.ps1 -ImageFile "\\nas\Share\example.png" -NotEnoughColors 'Reuse'

which will reuse colors instead where no good enough fit was found, or:

./poshwal.ps1 -ImageFile "\\nas\Share\example.png" -MapColorsByHue:$false

which disables any kind of "smart" assignment of colors and instead assigns them in descending order of their prevalence in the image. Since no colors are being discarded here for being a "bad fit" it maximizes your chances of enough colors having been extracted from the image to fill in all 16 slots. However if there weren't the behavior specified by -NotEnoughColors will still apply which is "Extrapolate" by default. To combat this without reusing colors, you can set the -SimilarColorThreshold to a lower value to allow more colors to be extracted from the image despite being increasingly similar and hard to differentiate.

Sample screenshots

I have uploaded some samples here: https://imgur.com/a/emb95A3

Building

The .ps1 script can be run autonomously, is easily editable and does not require compilation. The helper binary 'cpp_consoleattacher.exe' is only needed to re-color already opened terminal windows other than the one you're running poshwal from on the fly.

To compile the C++ binary yourself, download and install the Microsoft Visual C++ Build Tools or the full Visual Studio 2017. Open a "x64 Native Tools Command prompt for VS 2017" from the Start menu, cd to the directory with the source file and run cl cpp_consoleattacher.cpp /EHsc to compile it. For more details please refer to the Microsoft documentation on the VC++ Build tools cli.

Miscellaneous

1. If you do not specify an input image, the script will try to use your current wallpaper.
2. If you are not happy with a generated theme from a particular image try different values for the SimilarColorThreshold, RequiredBrightnessDifference and SimilarColorAlgorithm parameters as well as possibly -MapColorsByHue:$false (consult Get-Help) - that said the algorithm is not magic and won't be able to pull a theme you love out of every image ☹ please try a few!
3. The 'cpp_consoleattacher.exe' file is not necessary for the script to function, it is only needed to re-color other already opened terminals on the fly.
4. To use the generated theme in the new Windows Terminal, select the 'Generated by poshwal' theme for any profiles you want. This theme will be updated whenever the script is run.