red color becomes darker after transform png to webp

I’m using sharp to transform images, such as from png to webp format.

some red text in the final webp image, is darker than how it is in the origin png image.

I can’t find any config or arguments to fix this.

following is my code:

sharp( imageAbsolutePath )
        .webp({ quality : 100, alphaQuality : 100 })
        .toFile( webpAbsolutePath )
        .then( function( info ){
            info.webpPath = webpAbsolutePath;
            return info;
        });

This is the origin png image:

and this is the webp version:

[janwerkhoven]

🎉

I’ve found the solution: normalise the colour profile before converting to WEBP.

convert "image.png" -profile "./sRGB_v4_ICC_preference.icc" "normalised.png"

cwebp "normalised.png" -o "image.webp"

Converting PNGs exported by Capture One to WEBP resulted in dark red WEBPs. PNGS exported by Sketch however, resulted in correctly coloured WEBPs. The difference is the colour profiles they use.

I used ImageMagick for converting the colour profile. Below is the ICC file that worked for me:

sRGB_v4_ICC_preference.icc.zip

[sophister]

@lovell Thx.

lossless : true solves this.