maybe will work

src/beautify-image-paths.js

@@ -2,16 +2,24 @@ const path = require("path");
 const markdownLinkExtractor = require("markdown-link-extractor");
 const isUrl = require("is-url");
 
-module.exports = (content, filePath) => {
+const isImg = filePath => {
+  const extName = path.parse(filePath).ext;
+
+  return extName === ".jpg" || extName === ".png" || extName === ".gif";
+};
+
+module.exports = ({ pathToStatic }) => (content, filePath) => {
   let markdown = content;
   const dir = path.dirname(filePath);
+  const static = path.resolve(process.cwd(), pathToStatic);
 
   markdownLinkExtractor(content)
     .filter(link => !isUrl(link))
+    .filter(isImg)
     .map(link => ({ origin: link, processed: path.resolve(dir, link) }))
     .map(({ origin, processed }) => ({
       origin,
-      processed: path.relative(process.cwd(), processed),
+      processed: path.relative(static, processed),
     }))
     .forEach(({ origin, processed }) => {
       markdown = markdown.replace(origin, processed);

src/markdown-combine.js

@@ -33,7 +33,7 @@ const combineMarkdowns = ({ contents, pathToStatic, mainMdFilename }) => async l
 
     try {
       const content = files
-        .map(({ content, name }) => beautifyImages(content, name))
+        .map(({ content, name }) => beautifyImages({ pathToStatic })(content, name))
         .join("\n\n\n\n");
       await writeFile(resultFilePath, content);
     } catch (e) {