diff --git a/cmd/main.go b/cmd/main.go
index a4d61ed..e585c1f 100755
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -8,9 +8,7 @@ import (
 	"image/draw"
 	"image/gif"
 	"image/jpeg"
-	_ "image/jpeg"
 	"image/png"
-	_ "image/png"
 	"log"
 	"os"
 	"path"
@@ -37,6 +35,9 @@ func main() {
 	}
 
 	img, err := os.Open(*source)
+	if err != nil {
+		log.Fatal("could not open source image:", err)
+	}
 	defer img.Close()
 
 	src, _, err := image.Decode(img)
@@ -46,7 +47,7 @@ func main() {
 	start := time.Now()
 	if *outputGif {
 		for i := 1; i <= *radius; i++ {
-			img, err := stackblur.Run(src, uint32(i))
+			img, err := stackblur.Process(src, uint32(i))
 			if err != nil {
 				log.Fatal(err)
 			}
@@ -67,7 +68,7 @@ func main() {
 			log.Fatal(err)
 		}
 	} else {
-		img, err := stackblur.Run(src, uint32(*radius))
+		img, err := stackblur.Process(src, uint32(*radius))
 		if err != nil {
 			log.Fatal(err)
 		}
@@ -76,7 +77,7 @@ func main() {
 		}
 	}
 	end := time.Since(start)
-	fmt.Printf("\nGenerated in: %.2fs\n", end.Seconds())
+	fmt.Printf("Generated in: %.2fs\n", end.Seconds())
 }
 
 // encodeGIF encodes the generated output into a gif file
@@ -100,6 +101,9 @@ func encodeGIF(imgs []image.Image, path string) error {
 // generateImage generates the image type depending on the provided extension
 func generateImage(dst string, img image.Image) error {
 	output, err := os.OpenFile(dst, os.O_CREATE|os.O_RDWR, 0755)
+	if err != nil {
+		return err
+	}
 	defer output.Close()
 
 	if err != nil {
diff --git a/go.mod b/go.mod
index 42d6a55..abfdbd1 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,12 @@
 module github.com/esimov/stackblur-go
 
-go 1.13
+go 1.16
+
+// Provides an unstable API
+retract v1.0.0
+
+// Introduces backwards incompatible changes
+retract v1.0.1
+
+// Also makes a backwards incompatible change
+retract v1.0.2
diff --git a/stackblur.go b/stackblur.go
index 92e0d03..aa759be 100755
--- a/stackblur.go
+++ b/stackblur.go
@@ -7,8 +7,6 @@ import (
 	"errors"
 	"image"
 	"image/color"
-	"io"
-	"os"
 )
 
 // blurStack is a linked list containing the color value and a pointer to the next struct.
@@ -55,27 +53,15 @@ var shgTable = []uint32{
 	24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
 }
 
-// Run takes an image or pixel data as input and returns
-// it's blurred version by applying the blur radius defined as parameter.
-func Run(input interface{}, radius uint32) (image.Image, error) {
+// Process takes the source image and returns it's blurred version by applying the blur radius defined as parameter.
+func Process(src image.Image, radius uint32) (*image.NRGBA, error) {
 	var (
 		stackEnd *blurStack
 		stackIn  *blurStack
 		stackOut *blurStack
-		src      interface{}
-		err      error
 	)
-	switch input.(type) {
-	case *os.File:
-		src, _, err = image.Decode(input.(io.Reader))
-		if err != nil {
-			return nil, err
-		}
-	default:
-		src = input
-	}
 
-	var width, height = uint32(src.(image.Image).Bounds().Dx()), uint32(src.(image.Image).Bounds().Dy())
+	var width, height = uint32(src.Bounds().Dx()), uint32(src.Bounds().Dy())
 	var (
 		div, widthMinus1, heightMinus1, radiusPlus1, sumFactor uint32
 		x, y, i, p, yp, yi, yw,
@@ -94,7 +80,7 @@ func Run(input interface{}, radius uint32) (image.Image, error) {
 		return nil, errors.New("blur radius must be greater than 0")
 	}
 
-	img := toNRGBA(src.(image.Image))
+	img := toNRGBA(src)
 
 	div = radius + radius + 1
 	widthMinus1 = width - 1