Reimager User Guide

Welcome to Reimager

Reimager is a fast, private, and professional-grade image conversion tool for macOS.

It converts, resizes, and optimizes your photos, all locally on your Mac, without ever uploading your files to the cloud.

🚀 Getting Started

1. Launch Reimager

Drag Reimager to your Applications folder, then open it.
You’ll see the main window with a large drop zone.

**2. Make presets before adding images:**

Select your desired Format from the dropdown
- WebP, JPEG, PNG, HEIC, JXL, TIFF
Leave the size field empty to keep the sizes, or to resize:
- Enter width and height in pixels (or just the width)
- Enter the percentage change (from 1% to 400%)
Choose to strip or keep metadata (EXIF, IPTC, GPS, etc.)
Select output quality / compression
Select extension behavior
- Append extension example (filename.jpg -> filename.jpg.webp)
- Replace extension example (filename.jpg -> filename.webp)
Under Destination, choose:
- Source Folder: saves next to your originals, or
- Custom Folder: choose another location.

💡 Tip: When saving to a folder for the first time, macOS will ask for permission. This ensures Reimager can safely write files there. You’ll only need to grant permission once per folder. You can choose a higher level to grant access in order to not have to grant subfolders each time, or just select permissions to the folders you need.

3. Create additional presets for output files if desired (or remove any)

4. Add files

Add folders (including nested folders) or files
Compatible files formats include:
- JPEG, AVIF, ARW, CR2, DNG, PNG, TIFF, GIF, BMP, HEIC, RAW, WebP variants and more

💡 Tip: You can continue to add files and folders before running the queue. If you need to make changes to presets or settings, click the Update Queue button. You can clear the entire queue or removed selected files to clear.

5. Start converting

Click Start Conversion.
Status icon for each file will change from gray to blue when processing.
Status icon for each file will change to green when finished successfully.
Status icon will turn red if something goes wrong and will be reported in the log.
You can click cancel at any time, but it may take a while to finish files that are currently in the middle of processing.
When finished, you’ll see a summary showing the start time, number of files converted and the amount of time it took. Verbose mode (see app settings) provides additional details.

💡 Tip: If you have another job to do, you can open a new tab or window, set it up and even start processing. Be careful not to do this with the same output folders if the names will conflict as conflicting name protection is only per job.

⚙️ App Settings

Turbo mode: This allows parallel processing using multiple cores available on your Mac. Turn this on for the fastest conversion results, especially for long queues. However, since this consumes more processing resources, you might want to run sequentially, freeing up those resources.
Resize mode: You can use the exact dimensions specified, or you can set it so that it fits within the width or height, which is ideal for landscape or portrait picture frames
JPEG extension: You can select your JPEG files to end with .jpeg or .jpg. This allows for better compatibility with systems or apps that only accept one or the other.
Dimensions to file names: You can append the dimensions to the filename whether it’s specified in the resize field as dimensions or as percentage.
Presets: You can save presets as workflows and reload them as needed. This is useful for setting up things like presets for clients so you don’t need to look up and enter each preset with each job. Presets are wiped when App Settings are reset.
Verbose log reporting: Verbose can be useful if something is going wrong, but otherwise it’s likely you’d want concise reporting.

🛡️ Privacy and Security

Reimager performs all processing entirely on your Mac.

Your images never leave your device: no uploads, no analytics, no tracking, no ads, no cookies.

When using a Custom Folder, macOS may ask for write access. If you click Cancel, the current queue safely stops and nothing is written.

🧠 Best Practices

Use WebP or JXL for web optimization (results in smaller files at same quality).
Use TIFF, PNG for lossless work.
Strip metadata before publishing photos online for privacy.
Keep originals if you’re testing different compression levels.
Always backup and archive.
If you try to quit or close Reimager while conversions are running, you’ll be asked to confirm first, protecting against partial or incomplete conversions. There’s a Cancel All on the top right of the app which should be used instead.

🩵 Need Help?

From the menu bar, choose:

Help → Reimager User Guide (you’re here!)

or Contact Us

❓ Frequently Asked Questions (FAQ)

1. Why does Reimager ask for folder access?

macOS sandboxing requires explicit permission before apps can write to arbitrary folders.

Reimager requests this once per destination. Your approval is stored securely and never shared.

2. Why does it show “Write permission not granted” after I click Cancel?

That’s normal. It means you chose not to allow access.

Reimager cancels the queue safely instead of forcing writes.

3. Why not just use a free online converter?

Online converters often upload your files to third-party servers, which is slower and can compromise privacy.

Reimager runs locally, instantly, offline, no ads, and with no subscription.

4. Can I convert folders recursively?

Yes. When you drop a folder, Reimager automatically scans all subfolders for supported images.

5. Does it overwrite existing files?

Yes, it can. Reimager scans output location for overwrite and warns, but you’re able to override this warning. You should always have a backup archive in case the results aren’t what you desire.

6. What’s the difference between WebP, JPEG, PNG, HEIC, JPEG XL and TIFF?

The short answer is:
WebP is currently has the best combination of being modern and accepted format for web newer web browsers.

JPEG is the most widely compatible format, but is also the oldest and lacks benefits of the other newer formats.

PNG is also an older format but has lossless and transparency capabilities.

HEIC is the advanced format Apple uses on iPhones and in Apple Photos and isn’t always compatible with other software.

JPEG XL is relatively new in terms of adoption, but offers the best quality to size ratio.

TIFF is lossless and used often for archiving or as an intermediary format for work/collaboration before final export to an end format like one of the above.

See our comparison page for a long answer.

7. Why is quality disabled for PNG and TIFF?

The quality slider is disabled for lossless formats.

💡 Tip: You can click the TIFF selection to toggle between the following lossless TIFF formats:

No compression: Fast, but with much larger file sizes.
ZIP compression: Often compresses photographic content better, but may not open in older TIFF readers or legacy software. Much slower.
LZW compression: Fast, broadly compatible, and good for simple images.

8. How do I reset preferences?

Choose Help → Reset App Preferences…

This clears saved destinations and restores defaults. You will lose all saved presets.

9. How do I clear app cache and why would I?

Choose Help → Clear App Cache

Some formats need lossless temporary intermediaries during the transcoding. These are cleared automatically by default during the queue processing, but data can get left behind if the app is improperly terminated. This feature gives users the ability to clear unneeded data that could otherwise bloat their Mac.

10. Where are converted files saved?

If Source Folder is selected, new files appear in the same folder and next to the original files.

If Custom Folder is selected, they go there instead.

11. Can I get a refund or move my license to another Mac?

If you purchased through the Mac App Store, Apple manages refunds and licenses via:

reportaproblem.apple.com

Version History

Change log is as follows:

v1.0 (August 2025) – Reimager is born
v1.1 (October 2025) – First Apple App Store version