Convert wide-gamut images to sRGB before uploading

Tusker/Models/CompositionAttachmentData.swift

@@ -69,13 +69,22 @@ enum CompositionAttachmentData {
                     }
                     
                     let utType: UTType
-                    if dataUTI == "public.heic" {
-                        // neither Mastodon nor Pleroma handles HEIC well, so convert to JPEG
                     let image = CIImage(data: data)!
+                    let needsColorSpaceConversion = image.colorSpace?.name != CGColorSpace.sRGB
+    
+                    // neither Mastodon nor Pleroma handles HEIC well, so convert to JPEG
+                    // they also do a bad job converting wide color gamut images (they seem to just drop the profile, letting the wide-gamut values be reinterprete as sRGB)
+                    // if that changes in the future, we'll need to pass the InstanceFeatures in here somehow and gate the conversion
+                    if needsColorSpaceConversion || dataUTI == "public.heic" {
                         let context = CIContext()
-                        let colorSpace = image.colorSpace ?? CGColorSpace(name: CGColorSpace.sRGB)!
+                        let sRGB = CGColorSpace(name: CGColorSpace.sRGB)!
-                        data = context.jpegRepresentation(of: image, colorSpace: colorSpace, options: [:])!
+                        if dataUTI == "public.png" {
+                            data = context.pngRepresentation(of: image, format: .ARGB8, colorSpace: sRGB)!
+                            utType = .png
+                        } else {
+                            data = context.jpegRepresentation(of: image, colorSpace: sRGB)!
                             utType = .jpeg
+                        }
                     } else {
                         utType = UTType(dataUTI)!
                     }