Imagesharp: Opacity() effect doesn't work / .net4.5 /.netstandard1.1/ Win10

[jtorjo]

Prerequisites

• [x] I have written a descriptive issue title
• [x] I have verified that I am running the latest version of ImageSharp
• [x] I have verified if the problem exist in both DEBUG and RELEASE mode
• [x] I have searched open and closed issues to ensure it has not already been reported

Description

Applying Opacity() Filter leaves the image unchanged.

Steps to Reproduce

Image<Rgba32> src_image;
using (FileStream stream = File.OpenRead(src_file_name))
    src_image = SixLabors.ImageSharp.Image.Load(stream);
src_image.Mutate( x => x.Opacity( .1));
using (FileStream output = File.OpenWrite(dest_file_name_))
    dest_image.Save(output, new JpegEncoder());

System Configuration

.net4.5 /.netstandard1.1/ Win10

• ImageSharp version: 1.0.0.beta00003
• Other ImageSharp packages and versions: core 1.0.0-beta0005, Drawing: 1.0.0-beta0003
• Environment (Operating system, version and so on): Win10, Visual Studio 2017, v15.6.6
• .NET Framework version: .net4.5
• Additional information: all other tried filters work (and I tried pretty much all the others :))

[JimBobSquarePants]

Jpegs don't support opacity.

[jtorjo]

Lol, I'm an idiot :)

[JimBobSquarePants]

😄 Happens to the best of us.

Thanks for filling in the issue template properly though, really appreciate it 👍

[jtorjo]

Sure thing! You guys rock big time! I can't emphasize how much I LOVE your lib!

[antonfirsov]

@jtorjo gonna check out your LogWizard tool, cuz it might be useful for my job. So thanks for making this mistake! :)

[jtorjo]

@antonfirsov Cool! Let me know what you think of it. It's been a long time since I worked on it, since my job took me elsewhere, but for short additions/requests, I may have a bit of time now and then ;)