diff --git a/nextflow.config b/nextflow.config
index 3c8efce9..f5d8e226 100755
--- a/nextflow.config
+++ b/nextflow.config
@@ -28,6 +28,7 @@ params {
 	clair3_docker_name = "hkubal/clair3:latest"  // used for variant call
 	deepsignal2_docker_name = "liuyangzzu/deepsignal2:v1.0" // used for deepsignal v2
 	guppy_stable_name = "liuyangzzu/guppy_stable:v6.3.8"  // solve issues for guppy meth call in v6.4.6
+	preprocessing_docker_name = "liuyangzzu/preprocessing" // for untar preprocessing
 
 	// process and executor configurations
 	executor = null
@@ -268,6 +269,9 @@ profiles {
 			container = params.docker_name
 			containerOptions = params.containerOptions // or "--gpus all" Note: this is not compatible with GitHub citest/naive docker users
 
+			withName: 'UNTAR' {
+				container = params.preprocessing_docker_name
+			}
 			withName: 'Tombo|DeepMod|METEORE' {
 				container = params.tombo_docker_name
 			}
@@ -304,6 +308,10 @@ profiles {
 			container = params.singularity_name
 			containerOptions = params.containerOptions // "--nv"
 
+			withName: 'UNTAR' {
+				container = params.preprocessing_docker_name.startsWith("/") ?
+								params.preprocessing_docker_name : "docker://${params.tombo_docker_name}"
+			}
 			withName: 'Tombo|DeepMod|METEORE' {
 				// container = "docker://${params.tombo_docker_name}"
 				// reserve local image for singularity, or append docker:// header for online image