isolate signature in images

processor.go

@@ -83,7 +83,8 @@ func subThumbnail(url string) string {
 		Height: 400,
 	}
 	path := imagorpath.Generate(params, imagorpath.NewHMACSigner(sha256.New, 0, key))
-	return path
+	signature := path[:strings.IndexByte(path, '/')]
+	return signature
 }
 
 // Process implements imagor.Processor interface
@@ -156,7 +157,8 @@ func (p *Processor) Process(ctx context.Context, in *imagor.Blob, params imagorp
 		case "og:image":
 			fallthrough
 		case "twitter:image:src":
-			meta.Image = subThumbnail(val)
+			meta.ImageSignature = subThumbnail(val)
+			meta.Image = val
 			break
 
 		case "og:title":
@@ -190,6 +192,7 @@ type Metadata struct {
 	Title          string            `json:"title"`
 	Description    string            `json:"description"`
 	Image          string            `json:"image"`
+	ImageSignature string            `json:"image_signature"`
 	Hostname       string            `json:"hostname"`
 	SpecialHandler string            `json:"special_handler"`
 	SpecialData    map[string]string `json:"special_data"`