diff --git a/rawtherapee.js b/rawtherapee.js
new file mode 100644
index 0000000..aa76d68
--- /dev/null
+++ b/rawtherapee.js
@@ -0,0 +1,175 @@
+const fs = require('fs')
+const { spawn } = require('child_process')
+
+const defaultOptions = {
+  replace: false,
+  allFormats: false,
+  presets: ['default'],
+  ignoreBadPreset: false,
+  output: '.',
+  format: 'jpg',
+  depth: 8,
+  compression: 90,
+  subSampling: 2,
+  zip: false,
+  onChange: () => {}
+}
+
+const o2cli = (options) => {
+  const params = ['-q']
+  const {
+    replace,
+    allFormats,
+    presets,
+    ignoreBadPreset,
+    output,
+    format,
+    compression,
+    subSampling,
+    zip,
+    depth
+  } = options
+  if (replace) params.push('-Y')
+  if (allFormats) params.push('-a')
+  if (presets || presets.length) {
+    presets.forEach((preset) => {
+      switch (preset) {
+        case 'default':
+          return params.push('-d')
+        case 'sidecar':
+          return params.push('-s')
+        case 'sidecar-strict':
+          return params.push('-S')
+        default:
+          if (!fs.existsSync(preset)) {
+            const err = new Error(`Preset '${preset}' not found.`)
+            if (!ignoreBadPreset) throw err
+            else if (process.env.DEBUG) console.error(err)
+          } else {
+            params.push('-p')
+            params.push(preset)
+          }
+      }
+    })
+  }
+  if (format) {
+    switch (format.toLowerCase()) {
+      case 'jpg':
+      case 'jpeg':
+        params.push(`-j${compression || ''}`)
+        if (subSampling) {
+          switch (subSampling) {
+            case '4:2:0':
+            case 1:
+              params.push('-js1')
+              break
+            case '4:2:2':
+            case 2:
+              params.push('-js2')
+              break
+            case '4:4:4':
+            case 3:
+              params.push('-js3')
+              break
+            default:
+              console.warn(
+                `Warning: subSampling '${subSampling}' is unknown. Option is ignored, 'rawtherapee-cli' will use his own default (4:2:2).`
+              )
+          }
+        }
+        break
+      case 'png':
+        params.push('-n')
+        break
+      case 'tif':
+      case 'tiff':
+        params.push(`-t${zip && 'z'}`)
+        break
+    }
+  }
+  if (depth) params.push(`-b${depth}`)
+  if (output) {
+    params.push('-o')
+    params.push(output)
+  }
+  return params
+}
+
+const rawtherapee = (file, options = {}) => {
+  options = { ...defaultOptions, ...options }
+  const { onChange } = options
+  return new Promise((resolve, reject) => {
+    let ckf = file
+    let filename
+    if (!Array.isArray(file)) ckf = [file]
+    if ((filename = ckf.find((fl) => !fs.existsSync(fl)))) {
+      return reject(new Error(`File ${filename} not found`))
+    }
+    const params = o2cli(options)
+    params.push('-c')
+    params.push(file)
+    const rwtp = spawn('rawtherapee-cli', params)
+
+    const files = []
+
+    rwtp.stdout.on('data', (buf) => {
+      const data = buf.toString('utf8')
+      let ipath = /Processing: (.+)$/im.exec(data)
+      if (ipath) {
+        if (files.length) {
+          onChange({
+            status: 'complete',
+            file: files[files.length - 1]
+          })
+        }
+        files.push(ipath[1])
+        onChange({
+          status: 'processing',
+          file: ipath[1]
+        })
+      }
+      if (!ipath) {
+        ipath = /^RawTherapee, version ([0-9.]+), command line./im.exec(data)
+        if (ipath) {
+          onChange({
+            status: 'start',
+            version: ipath[1]
+          })
+        }
+      }
+      if (!ipath) {
+        ipath = /^"(.+)".*image skipped/im.exec(data)
+        if (ipath) {
+          onChange({
+            status: 'skipped',
+            file: ipath[1]
+          })
+        }
+      }
+      if (!ipath && process.env.DEBUG) console.warn('not handled', data)
+    })
+
+    rwtp.stderr.on('data', (data) => {
+      console.error(`stderr: ${data}`)
+      reject(new Error(data))
+    })
+    rwtp.on('error', (data) => {
+      console.error(`error: ${data}`)
+      reject(new Error(data))
+    })
+
+    rwtp.on('close', (code) => {
+      if (code > 0) return reject(new Error(`rawtherapee-cli process exited with code ${code}`))
+      if (files.length) {
+        onChange({
+          status: 'complete',
+          file: files[files.length - 1]
+        })
+      }
+      onChange({ status: 'idle', code })
+      resolve(files)
+    })
+  })
+}
+
+module.exports = rawtherapee