diff --git a/libimagentryfilter/src/builtin/header/field_eq.rs b/libimagentryfilter/src/builtin/header/field_eq.rs
index 5617a42b..eeef5aa7 100644
--- a/libimagentryfilter/src/builtin/header/field_eq.rs
+++ b/libimagentryfilter/src/builtin/header/field_eq.rs
@@ -1,22 +1,34 @@
 use libimagstore::store::Entry;
 
 use builtin::header::field_path::FieldPath;
+use builtin::header::field_predicate::FieldPredicate;
+use builtin::header::field_predicate::Predicate;
 use filter::Filter;
 
 use toml::Value;
 
+struct EqPred {
+    expected: Value
+}
+
+impl Predicate for EqPred {
+
+    fn evaluate(&self, v: Value) -> bool {
+        self.expected == v
+    }
+
+}
+
 /// Check whether certain header field in a entry is equal to a value
 pub struct FieldEq {
-    header_field_path: FieldPath,
-    expected_value: Value
+    filter: FieldPredicate<EqPred>,
 }
 
 impl FieldEq {
 
     pub fn new(path: FieldPath, expected_value: Value) -> FieldEq {
         FieldEq {
-            header_field_path: path,
-            expected_value: expected_value,
+            filter: FieldPredicate::new(path, Box::new(EqPred { expected: expected_value })),
         }
     }
 
@@ -25,10 +37,7 @@ impl FieldEq {
 impl Filter for FieldEq {
 
     fn filter(&self, e: &Entry) -> bool {
-        e.get_header()
-            .read(&self.header_field_path[..])
-            .map(|val| val.map(|v| v == self.expected_value).unwrap_or(false))
-            .unwrap_or(false)
+        self.filter.filter(e)
     }
 
 }
diff --git a/libimagentryfilter/src/builtin/header/field_grep.rs b/libimagentryfilter/src/builtin/header/field_grep.rs
index 2c28c9cf..aac42207 100644
--- a/libimagentryfilter/src/builtin/header/field_grep.rs
+++ b/libimagentryfilter/src/builtin/header/field_grep.rs
@@ -4,20 +4,35 @@ use toml::Value;
 use libimagstore::store::Entry;
 
 use builtin::header::field_path::FieldPath;
+use builtin::header::field_predicate::FieldPredicate;
+use builtin::header::field_predicate::Predicate;
 use filter::Filter;
 
+struct EqGrep{
+    regex: Regex
+}
+
+impl Predicate for EqGrep {
+
+    fn evaluate(&self, v: Value) -> bool {
+        match v {
+            Value::String(s) => self.regex.captures(&s[..]).is_some(),
+            _                 => false,
+        }
+    }
+
+}
+
 /// Check whether certain header field in a entry is equal to a value
 pub struct FieldGrep {
-    header_field_path: FieldPath,
-    grep: Regex,
+    filter: FieldPredicate<EqGrep>,
 }
 
 impl FieldGrep {
 
     pub fn new(path: FieldPath, grep: Regex) -> FieldGrep {
         FieldGrep {
-            header_field_path: path,
-            grep: grep,
+            filter: FieldPredicate::new(path, Box::new(EqGrep { regex: grep})),
         }
     }
 
@@ -26,15 +41,7 @@ impl FieldGrep {
 impl Filter for FieldGrep {
 
     fn filter(&self, e: &Entry) -> bool {
-        e.get_header()
-            .read(&self.header_field_path[..])
-            .map(|v| {
-                match v {
-                    Some(Value::String(s)) => self.grep.captures(&s[..]).is_some(),
-                    _                      => false,
-                }
-            })
-            .unwrap_or(false)
+        self.filter.filter(e)
     }
 
 }
diff --git a/libimagentryfilter/src/builtin/header/field_gt.rs b/libimagentryfilter/src/builtin/header/field_gt.rs
new file mode 100644
index 00000000..6975737b
--- /dev/null
+++ b/libimagentryfilter/src/builtin/header/field_gt.rs
@@ -0,0 +1,60 @@
+use libimagstore::store::Entry;
+
+use builtin::header::field_path::FieldPath;
+use builtin::header::field_predicate::FieldPredicate;
+use builtin::header::field_predicate::Predicate;
+use filter::Filter;
+
+use toml::Value;
+
+struct EqGt {
+    comp: Value
+}
+
+impl Predicate for EqGt {
+
+    fn evaluate(&self, v: Value) -> bool {
+        match &self.comp {
+            &Value::Integer(i) => {
+                match v {
+                    Value::Integer(j) => i > j,
+                    Value::Float(f) => (i as f64) > f,
+                    _ => false,
+                }
+            },
+            &Value::Float(f) => {
+                match v {
+                    Value::Integer(i) => f > (i as f64),
+                    Value::Float(d) => f > d,
+                    _ => false,
+                }
+            },
+            _ => false,
+        }
+    }
+
+}
+
+/// Check whether certain header field in a entry is equal to a value
+pub struct FieldGt {
+    filter: FieldPredicate<EqGt>,
+}
+
+impl FieldGt {
+
+    pub fn new(path: FieldPath, expected_value: Value) -> FieldGt {
+        FieldGt {
+            filter: FieldPredicate::new(path, Box::new(EqGt { comp: expected_value })),
+        }
+    }
+
+}
+
+impl Filter for FieldGt {
+
+    fn filter(&self, e: &Entry) -> bool {
+        self.filter.filter(e)
+    }
+
+}
+
diff --git a/libimagentryfilter/src/builtin/header/field_isempty.rs b/libimagentryfilter/src/builtin/header/field_isempty.rs
index a6a5b3d3..a7ff4ab1 100644
--- a/libimagentryfilter/src/builtin/header/field_isempty.rs
+++ b/libimagentryfilter/src/builtin/header/field_isempty.rs
@@ -30,7 +30,7 @@ impl Filter for FieldIsEmpty {
                     Some(Value::Boolean(_)) => false,
                     Some(Value::Float(_))   => false,
                     Some(Value::Integer(_)) => false,
-                    Some(Value::String(_))  => false,
+                    Some(Value::String(s))  => s.is_empty(),
                     Some(Value::Table(t))   => t.is_empty(),
                     _                       => true,
                 }
diff --git a/libimagentryfilter/src/builtin/header/field_istype.rs b/libimagentryfilter/src/builtin/header/field_istype.rs
index 6ff6d511..8423c0ab 100644
--- a/libimagentryfilter/src/builtin/header/field_istype.rs
+++ b/libimagentryfilter/src/builtin/header/field_istype.rs
@@ -1,6 +1,8 @@
 use libimagstore::store::Entry;
 
 use builtin::header::field_path::FieldPath;
+use builtin::header::field_predicate::FieldPredicate;
+use builtin::header::field_predicate::Predicate;
 use filter::Filter;
 
 use toml::Value;
@@ -31,17 +33,27 @@ impl Type {
 
 }
 
+struct IsTypePred {
+    ty: Type
+}
+
+impl Predicate for IsTypePred {
+
+    fn evaluate(&self, v: Value) -> bool {
+        self.ty.matches(&v)
+    }
+
+}
+
 pub struct FieldIsType {
-    header_field_path: FieldPath,
-    expected_type: Type,
+    filter: FieldPredicate<IsTypePred>,
 }
 
 impl FieldIsType {
 
     pub fn new(path: FieldPath, expected_type: Type) -> FieldIsType {
         FieldIsType {
-            header_field_path: path,
-            expected_type: expected_type,
+            filter: FieldPredicate::new(path, Box::new(IsTypePred { ty: expected_type })),
         }
     }
 
@@ -50,10 +62,7 @@ impl FieldIsType {
 impl Filter for FieldIsType {
 
     fn filter(&self, e: &Entry) -> bool {
-        e.get_header()
-            .read(&self.header_field_path[..])
-            .map(|val| val.map(|v| self.expected_type.matches(&v)).unwrap_or(false))
-            .unwrap_or(false)
+        self.filter.filter(e)
     }
 
 }
diff --git a/libimagentryfilter/src/builtin/header/field_lt.rs b/libimagentryfilter/src/builtin/header/field_lt.rs
new file mode 100644
index 00000000..15558d4b
--- /dev/null
+++ b/libimagentryfilter/src/builtin/header/field_lt.rs
@@ -0,0 +1,60 @@
+use libimagstore::store::Entry;
+
+use builtin::header::field_path::FieldPath;
+use builtin::header::field_predicate::FieldPredicate;
+use builtin::header::field_predicate::Predicate;
+use filter::Filter;
+
+use toml::Value;
+
+struct EqLt {
+    comp: Value
+}
+
+impl Predicate for EqLt {
+
+    fn evaluate(&self, v: Value) -> bool {
+        match &self.comp {
+            &Value::Integer(i) => {
+                match v {
+                    Value::Integer(j) => i < j,
+                    Value::Float(f) => (i as f64) < f,
+                    _ => false,
+                }
+            },
+            &Value::Float(f) => {
+                match v {
+                    Value::Integer(i) => f < (i as f64),
+                    Value::Float(d) => f < d,
+                    _ => false,
+                }
+            },
+            _ => false,
+        }
+    }
+
+}
+
+/// Check whether certain header field in a entry is equal to a value
+pub struct FieldLt {
+    filter: FieldPredicate<EqLt>,
+}
+
+impl FieldLt {
+
+    pub fn new(path: FieldPath, expected_value: Value) -> FieldLt {
+        FieldLt {
+            filter: FieldPredicate::new(path, Box::new(EqLt { comp: expected_value })),
+        }
+    }
+
+}
+
+impl Filter for FieldLt {
+
+    fn filter(&self, e: &Entry) -> bool {
+        self.filter.filter(e)
+    }
+
+}
+
diff --git a/libimagentryfilter/src/builtin/header/field_predicate.rs b/libimagentryfilter/src/builtin/header/field_predicate.rs
new file mode 100644
index 00000000..5dddc46e
--- /dev/null
+++ b/libimagentryfilter/src/builtin/header/field_predicate.rs
@@ -0,0 +1,45 @@
+use libimagstore::store::Entry;
+
+use builtin::header::field_path::FieldPath;
+use filter::Filter;
+
+use toml::Value;
+
+pub trait Predicate {
+    fn evaluate(&self, Value) -> bool;
+}
+
+/// Check whether certain header field in a entry is equal to a value
+pub struct FieldPredicate<P: Predicate> {
+    header_field_path: FieldPath,
+    predicate: Box<P>,
+}
+
+impl<P: Predicate> FieldPredicate<P> {
+
+    pub fn new(path: FieldPath, predicate: Box<P>) -> FieldPredicate<P> {
+        FieldPredicate {
+            header_field_path: path,
+            predicate: predicate,
+        }
+    }
+
+}
+
+impl<P: Predicate> Filter for FieldPredicate<P> {
+
+    fn filter(&self, e: &Entry) -> bool {
+        e.get_header()
+            .read(&self.header_field_path[..])
+            .map(|val| {
+                match val {
+                    None => false,
+                    Some(v) => (*self.predicate).evaluate(v),
+                }
+            })
+            .unwrap_or(false)
+    }
+
+}
+
+
diff --git a/libimagentryfilter/src/builtin/header/mod.rs b/libimagentryfilter/src/builtin/header/mod.rs
index 886e5ce6..baece9f6 100644
--- a/libimagentryfilter/src/builtin/header/mod.rs
+++ b/libimagentryfilter/src/builtin/header/mod.rs
@@ -1,6 +1,9 @@
 pub mod field_eq;
 pub mod field_exists;
 pub mod field_grep;
+pub mod field_gt;
 pub mod field_isempty;
 pub mod field_istype;
+pub mod field_lt;
 pub mod field_path;
+pub mod field_predicate;