diff --git a/src/config-default.ts b/src/config-default.ts
index b0f0d3d..904b93f 100644
--- a/src/config-default.ts
+++ b/src/config-default.ts
@@ -26,7 +26,7 @@ const default_options: Options = {
     },
     cdn: {
       process: 'off',
-      src_include: /^.*$/,
+      src_include: null,
       src_exclude: null,
     },
     compress: true,
diff --git a/src/config-types.ts b/src/config-types.ts
index 938aa45..1204f34 100644
--- a/src/config-types.ts
+++ b/src/config-types.ts
@@ -43,7 +43,7 @@ export type Options = {
       process:
         | 'off' //default
         | 'optimize';
-      src_include: RegExp;
+      src_include: RegExp | null;
       src_exclude: RegExp | null;
       transformer?: UrlTransformer; // Custom 'unpic' cdn url transformer, if not present it will be determined by 'unpic' based on original url
     };
diff --git a/src/optimize.ts b/src/optimize.ts
index d90820e..0e41d84 100755
--- a/src/optimize.ts
+++ b/src/optimize.ts
@@ -329,59 +329,65 @@ async function processImage(
   /*
    * Check for external images
    */
-  if (!isLocal(attrib_src)) {
-    switch (config.image.cdn.process) {
-      case 'off':
-        break;
-      case 'optimize':
-        let cdnTransformer = config.image.cdn.transformer;
-        if (!cdnTransformer) {
-          const canonical = getCanonicalCdnForUrl(attrib_src);
-          if (!canonical) break;
-          cdnTransformer = getTransformer(canonical.cdn);
-        }
-        if (!cdnTransformer) break;
-        if (
-          !isIncluded(
-            attrib_src,
-            config.image.cdn.src_include,
-            config.image.cdn.src_exclude
-          )
-        )
-          break;
-        let attrib_width = getIntAttr(img, 'width');
-        if (!attrib_width) {
-          $state.reportIssue(htmlfile, {
-            type: 'warn',
-            msg: `Missing or malformed'width' attribute for image ${attrib_src}, unable to perform CDN transform`,
-          });
-          return;
-        }
-        let attrib_height = getIntAttr(img, 'height');
-        if (!attrib_height) {
-          $state.reportIssue(htmlfile, {
-            type: 'warn',
-            msg: `Missing or malformed 'height' attribute for image ${attrib_src}, unable to perform CDN transform`,
-          });
-          return;
-        }
-        const new_srcset = await generateSrcSetForCdn(
-          attrib_src,
-          cdnTransformer,
-          attrib_width,
-          attrib_height
+  switch (config.image.cdn.process) {
+    case 'off':
+      break;
+    case 'optimize':
+      let cdnTransformer = config.image.cdn.transformer;
+      if (cdnTransformer && !config.image.cdn.src_include) {
+        throw new Error(
+          'config.image.cdn.src_include is required when specifying a config.image.cdn.transformer'
         );
+      }
 
-        if (new_srcset !== null) {
-          img.attr('srcset', new_srcset);
-        }
-
-        // Add sizes attribute if not specified
-        if (img.attr('srcset') && !img.attr('sizes')) {
-          img.attr('sizes', '100vw');
-        }
+      if (!cdnTransformer) {
+        const canonical = getCanonicalCdnForUrl(attrib_src);
+        if (!canonical) break;
+        cdnTransformer = getTransformer(canonical.cdn);
+      }
+      if (!cdnTransformer) break;
+      if (
+        !isIncluded(
+          attrib_src,
+          config.image.cdn.src_include || /.*/,
+          config.image.cdn.src_exclude
+        )
+      )
+        break;
+      let attrib_width = getIntAttr(img, 'width');
+      if (!attrib_width) {
+        $state.reportIssue(htmlfile, {
+          type: 'warn',
+          msg: `Missing or malformed'width' attribute for image ${attrib_src}, unable to perform CDN transform`,
+        });
         return;
-    }
+      }
+      let attrib_height = getIntAttr(img, 'height');
+      if (!attrib_height) {
+        $state.reportIssue(htmlfile, {
+          type: 'warn',
+          msg: `Missing or malformed 'height' attribute for image ${attrib_src}, unable to perform CDN transform`,
+        });
+        return;
+      }
+      const new_srcset = await generateSrcSetForCdn(
+        attrib_src,
+        cdnTransformer,
+        attrib_width,
+        attrib_height
+      );
+
+      if (new_srcset !== null) {
+        img.attr('srcset', new_srcset);
+      }
+
+      // Add sizes attribute if not specified
+      if (img.attr('srcset') && !img.attr('sizes')) {
+        img.attr('sizes', '100vw');
+      }
+      return;
+  }
+  if (!isLocal(attrib_src)) {
     switch (config.image.external.process) {
       case 'off': // Don't process external images
         return;
diff --git a/src/utils/resource.ts b/src/utils/resource.ts
index bae2840..281139e 100644
--- a/src/utils/resource.ts
+++ b/src/utils/resource.ts
@@ -155,7 +155,6 @@ export class Resource {
 }
 
 export function isLocal(src: string) {
-   if (src.startsWith('/cdn_cgi/')) return false;
   const u = url.parse(src);
   return !u.host;
 }