Image Tool+ User Guide

Batch-convert images to next-generation web formats (WebP, AVIF, JPEG XL) and all the classics with a simple drag and drop. Image Tool+ is an image optimization app built for macOS, with an advanced engine for keeping HDR and gain maps intact.

HEIC WebP AVIF JPEG XL HDR JPEG PNG TIFF / BMP / GIF

Overview

Key Features

Simple, intuitive controls on top of a professional-grade image processing pipeline.

⚡️

Fast parallel batch processing

Converts several images at once across the cores of your Apple silicon CPU, so even thousands of photos or web assets are handled in one go.

🌈

HDR and gain maps preserved

HDR from iPhone and camera photos (gain maps, PQ / HLG) stays HDR when you convert to HEIC, AVIF, JPEG XL, PNG, or JPG. Formats that can't hold HDR, such as WebP, are converted to SDR.

🏷️

Batch renaming with numbers and sizes

Sequence numbers from 1 to 5 digits (1–00001), custom prefixes and suffixes, and the resized width or height added to file names automatically.

🔍

Live comparison preview

Check image quality, the change in file size, HDR headroom, and EXIF data before and after conversion with a split slider.

🎨

Watermarks, resizing, and metadata

Resize while keeping the aspect ratio, add a watermark with position, size, and opacity controls, and remove or batch-edit EXIF and GPS data.

Quick Start

Drag and drop images or folders, and you're ready to convert.

Drag and drop your images

Drag image files or folders onto the area in the middle of the Image Tool+ window that says “Drag & Drop images here.” Multiple files and nested folders are supported. You can also click the + button in the toolbar (⌘ + O) to choose files.

Choose output formats and quality

In the Encode section on the right side of the window, check the formats you want (WebP, AVIF, JPEG XL, and more) and adjust the Quality slider.

Click Start

Click the blue Start button at the top right of the toolbar, or press ⇧ + ⌘ + S. If you haven't chosen an output folder yet, a dialog opens so you can pick one. When conversion finishes, the files are saved to the output folder.

▲ The main window after converting images to WebP. The file list in the middle shows each file's converted size and how much smaller it got, the Status panel on the left keeps a history of what was processed, and the conversion settings are on the right

Format Guide

Format Settings Guide

From web optimization to high-quality archiving, here's what each format is good at and how to set it up. Defaults are the values the app uses the first time you launch it.

▲ WebP settings: the Quality slider, Lossless, Preset, Method, Keep Color Profile, and Sharp YUV

Setting	Default / Recommended	Description
Quality	`75` (web: 75–82)	Image quality for lossy compression. Around 75–80 matches or beats JPEG quality while cutting file size substantially.
Lossless	`Disable (Default)`	Lossless mode. Turn it on for illustrations, icons, and screenshots where not a single pixel should change.
Preset	`Default`	Uses libwebp's encoder tuning for the type of image (Photo / Picture / Drawing / Icon / Text).
Method	`4 (Default)`	The trade-off between compression and encoding speed (0–6). Use `6` for the smallest files.
Keep Color Profile	`Disable (Default)`	Embeds the ICC color profile. Turn it on for web photos whose wide color (such as Display P3) must be preserved exactly.
Sharp YUV	`Disable (Default)`	Uses a higher-quality RGB-to-YUV conversion that reduces color bleeding along edges. Ideal for images with text.

▲ AVIF settings: Lossless, Chroma Subsampling, Speed, Bit Depth, color settings (Color Primaries and more), and tiling

Setting	Default / Recommended	Description
Quality	`50` (web: 45–60)	Highly efficient compression built on the AV1 video codec. Even at 50, images look as good as a typical JPEG at 80–85.
Chroma Subsampling	`420` (default) / `444` (best quality)	Chroma subsampling (444 / 422 / 420 / 400). `420` gives the smallest files, `444` prevents color bleeding on thin red text and sharp edges, and `400` is grayscale.
Speed	`8 (recommended)`	Encoding speed (0–10). Higher numbers encode faster but produce larger files. Lower it to `4–6` when compression efficiency matters most.
Bit Depth	`0 Auto (default)`	Choose Auto, 8-bit, 10-bit, or 12-bit. Use 10-bit to avoid banding in HDR images and smooth gradients.

▲ JPEG XL settings: Lossless, Quality Mode, Effort, Progressive, and JPEG Recompress

Setting	Default / Recommended	Description
Quality	`75` (web: 75–85)	The main quality setting for JPEG XL, tuned closely to how people perceive images.
Effort	`7 (Default)`	How hard the encoder searches (1–10). 7 is the most practical balance of speed and compression.
JPEG Recompress	`Enable (Default)`	Converts existing 8-bit JPEGs to JPEG XL about 20% smaller with no quality loss at all (the original JPEG can be restored bit for bit).
Progressive	`Disable (Default)`	Enables progressive decoding, so images appear blurry at first and sharpen as they load on the web.

▲ HEIC settings: the Quality slider and Lossless

Setting	Default / Recommended	Description
Quality	`75` (recommended: 75–85)	HEIF/HEIC encoding quality. Uses native macOS / iOS hardware acceleration for fast, highly efficient compression.
Lossless	`Disable (Default)`	Writes at maximum quality (1.0). The macOS HEIC encoder has no true lossless mode, so the result is the highest possible quality with minimal loss rather than strictly lossless.
HDR (gain maps)	`Automatic (no setting)`	Photos with gain maps are saved as HEIC with gain maps, and PQ / HLG HDR is saved as 10-bit HDR (on macOS 15 and later, gain maps are written in ISO 21496-1 format). On HDR displays, bright highlights look just as they did in the original.

PNG

Check Lossy compression to reduce the image to a 256-color palette (8-bit indexed color) while keeping transparency, cutting file size by 60–70%. It's off by default.

JPEG

Besides the Quality slider, Optimize lets you choose jpegtran (lossless), which strips extra markers such as EXIF, or mozjpeg (lossy). Turn on Further compression (JPEG Archive) to recompress with a quality level (veryhigh to low) and a metric (ssim / ms-ssim), and optionally Subsampling.

TIFF / BMP / GIF

Convert to uncompressed TIFF for print, legacy BMP, and animated GIF. With Always Convert Animated Images to GIF turned on, animated images are saved as GIF whenever the output format is JPG, JPEG XL, PNG, HEIC, TIFF, or BMP (WebP and AVIF output stays animated).

Advanced Technology

HDR & Gain Map Preservation

When the output format can hold HDR, HDR photos from iPhone and other cameras keep their brightness after conversion.

💡 What is a gain map?

A gain map stores extra brightness information for the highlights as a separate layer alongside a standard (SDR) base image. On SDR displays the photo looks natural, and on HDR / XDR displays (such as the Liquid Retina XDR display on MacBook Pro), sunlight and neon glow brightly.

Output format	How HDR is handled
HEIC / AVIF	Photos with gain maps keep their gain maps, and PQ / HLG HDR is kept as 10-bit HDR (AVIF can also use 12-bit).
JPEG XL / PNG	HDR is kept as 16-bit PQ / HLG. Photos with gain maps are expanded to full HDR.
JPG	Saved as a JPEG with a gain map. A gain map is also created from PQ / HLG HDR.
WebP / TIFF / BMP / GIF	HDR isn't kept. Images are tone-mapped to SDR (sRGB, 8-bit).

Apple gain maps

Reads Apple-format gain maps in HEIC and JPG photos from the iPhone camera. On macOS 15 and later, they're rewritten in the international ISO 21496-1 format (on earlier versions of macOS they stay in Apple's format).

ISO 21496-1 standard

Gain maps are written in ISO 21496-1 format, and JPGs also carry Android Ultra HDR metadata, so HDR is more likely to display correctly on non-Apple platforms such as Android and Chrome.

SDR tone mapping

When you save to WebP, TIFF, BMP, or GIF, which can't hold HDR, Apple's tone mapping compresses the highlights to fit SDR while keeping clipping (blown-out highlights) to a minimum.

Quality Inspector

Comparison Preview

Check the balance between quality and file size before you convert, and compare the original and the result closely with the split slider. To open it, choose a format from the Preview menu in the toolbar or click a thumbnail in the list (you can also press ⇧ + ⌘ + P for the selected image).

▲ The preview window: drag the slider in the middle to compare the original (left) with the converted image (right). Here the ⓘ button (⌘I) overlays each side's file name, size, and color information, plus the original's EXIF data (camera, lens, focal length, shutter speed, aperture, ISO, date, and more). The converted image has no EXIF because Delete metadata is the default, but its color profile (sRGB) is kept because Keep Color Profile is set to Enable for WebP in this example

↔️ Split slider

Drag the slider left and right to compare compression noise and edge detail pixel by pixel.

📊 Live size reduction

Shows instantly, as a percentage, how much smaller (or larger) the file is than the original.

ℹ️ HDR / EXIF inspector

The ⓘ button in the toolbar (⌘ + I) overlays the color profile (sRGB, P3, Rec. 2020), HDR headroom, and camera data for both the original and the converted image.

Batch Renaming

Batch Rename & Filename Settings

A flexible, safe renaming engine that makes organizing web assets and photo shoots easy. Set it up in the Filename section on the right side of the window.

▲ Filename settings: Keep original filename extension, how to modify the filename (None / Prefix / Suffix / Replace) and the separator, and for Replace, the numbering digits, new name, prefix, and suffix. This example uses Replace with the prefix web, the new name product, the suffix thumb, the _ separator, and Numbering: 001, and the file list shows the new filenames

🔢 Rename with sequence numbers (Replace)

Choose Replace to replace the original file name with a sequence number of 1 to 5 digits (Numbering: 01, Numbering: 001 … Numbering: 00001). Combine it with an optional new name, prefix, and suffix; the number always comes last (for example, web_product_thumb_001.webp).

📐 Add the resized size automatically

With Prefix or Suffix, choose Resized width or height, or Resized width or height (with unit), to add the resized size to the file name (_1200 or _1200px). It's only added to images that were actually resized, not to images already smaller than the limit. Handy when exporting several sizes of responsive web assets (for srcset).

🔤 Separators and custom text

Choose (none), (space), -(hyphen), _(underline), or +(plus) as the separator. With Prefix or Suffix, you can also add your own text with Custom, or each image's position in the list with Order in list.

🛡️ Keep extensions & avoid name clashes

Turn on Keep original filename extension to keep the original extension, including its case, as in IMG_1234.JPG.webp. If a file with the same name already exists in the output folder, the new file is saved with a number, such as IMG_1234(1).webp, so nothing gets overwritten by accident (as long as Overwrite existing images is off).

Feature / setting	Example settings	Resulting file name (from `IMG_1234.JPG`)
Replace (numbering)	New name: `photo` / Numbering: 001 / separator `_`	`photo_001.webp`, `photo_002.webp`...
Prefix + Custom	`web` / separator `-`	`web-IMG_1234.webp`
Suffix + resized size	Resized width or height (with unit) / `_` (resized to a max width of 1200 px)	`IMG_1234_1200px.webp`
Keep the original extension	Keep original filename extension on	`IMG_1234.JPG.webp`

Editing Tools

Watermarks, Resizing & Metadata

Apply the edits you need for publishing and copyright protection in the same pass as the conversion.

▲ The Watermark window: drop a logo onto the preview area, then set when it's inserted, its position, size, offset, and opacity (here a 256 × 256 px logo sits at the bottom right with a −20 px offset and 85% opacity)

Logo and image watermarks

Drop a logo image such as a PNG, then set its Position (nine spots from Top left to Bottom right), Size (Original / Scaled / Relative / Absolute), Offset (X and Y in px or %), Opacity (0–100), and when it's inserted (Before resizing / After resizing). Offsets are positive to the right and down, so to move a bottom-right logo in from the edges, use negative values such as −20.

Resize with aspect ratio

Set a max width and max height in pixels (px) or percent (%). Images are scaled down to fit without changing their proportions, and they're never enlarged.

EXIF and location data

In the Metadata section, choose Preserve metadata, Delete metadata, or Edit metadata (Delete metadata is the default). With Edit metadata, you can write the artist, copyright, description, and keywords in bulk, or turn on Remove GPS location to strip just the location.

Preferences

Settings (Appearance, Input, Presets, Other)

In Settings (⌘ + ,), you can fine-tune how the app looks, which files it takes in, your presets, and the operating mode.

▲ Settings > Appearance: thumbnails, preview, status, and items to display in the sidebar

🖼️ Show or hide thumbnails

Choose whether the file list shows image thumbnails. When batch-processing tens of thousands of images, hiding thumbnails saves memory and keeps the list fast.

👆 Action when clicking a thumbnail

Choose what happens when you click a thumbnail in the list: Show conversion preview (the comparison slider, the default) or Show original image (opens the original in the app's own viewer).

🪟 Always on top

Keeps the comparison preview window floating above other windows so it never hides behind Finder or other apps. Handy when you compare often.

⚙️ Customize the sidebar

Turn each section of the right sidebar on or off: Presets, Encode, Resize, Watermark, Background Removal, Metadata, Input / Output, Filename, PDF Settings, and Post-conversion. Hide what you don't use to keep your workspace tidy.

▲ Settings > Input: bring the app to the front when dragging, limit file extensions, and register folders to ignore

⚡️ Bring the app to the front when dragging

When you start dragging files or folders from Finder or the desktop, Image Tool+ comes to the front automatically, so you can drop them even if its window is behind others. This is off by default.

🎯 Only process certain extensions (allow list)

Specify the image extensions to convert (for example, JPG,JPEG,PNG,WEBP,AVIF). Even if you drop a whole folder mixed with text, video, or ZIP files, only the matching images are loaded.

🚫 Ignore specific files & folders

Use the Register button to add folders that should be skipped when scanning, such as .git, node_modules, or folders of source files.

⚠️ Ignore files with extensions

List extensions to skip so intermediate or temporary files don't sneak into your batch.

▲ Settings > Presets: save the current settings as a new preset or update one, and export or import your settings

💾 Save and update presets

Name the settings you've adjusted in the sidebar (output formats, quality, resize limits, watermark position, metadata handling, and more) and save them with Save as.... Updating an existing preset takes a single click on Save.

⚡️ Switch instantly with shortcuts (`⌘` + `1–9`)

Recall a preset for each job, like "WebP for the web," "JPEG for social media," or "AVIF for high-res archives," from the Presets section of the sidebar or the Preset menu in the menu bar. ⌘ + 1–9 switches to presets 1–9, and ⌘ + 0 chooses None (no preset); your current settings stay as they are.

📤 Export settings

Export your presets and detailed settings to a file. It's a safe way to move to a new Mac or keep a backup.

📥 Import settings

Import an exported settings file to restore it. Share a common set of image optimization presets across a production or design team to keep quality consistent.

▲ Settings > Other: appearance, language, and operating mode (how many images are processed at once)

🌓 Appearance (System Default / Light / Dark)

Follow the macOS appearance setting, or keep the app in Light or Dark regardless of the system.

🌐 Language

Open System Preferences takes you straight to Language & Region > Applications in macOS, where you can choose the app's display language, such as English or Japanese.

🚀 Operating Mode (images processed at once)

Choose how many images are converted at the same time: Speed, Balance, or Stability (Balance is the default). Speed uses the larger of your CPU core count and 32, Balance uses the smaller of half your installed memory (in GB) and your CPU core count, and Stability processes two images at a time. Choose Stability to keep working comfortably while images convert, or Speed to use every core and finish as fast as possible.

Shortcuts

Keyboard Shortcuts

Use the keyboard to speed up your everyday image conversion work.

Main window

Shortcut	Command	Description
`⇧` + `⌘` + `S`	Start Conversion	Converts the images in the list to the formats you've chosen (same as the Start button in the toolbar).
`⇧` + `⌘` + `P`	Preview Result...	Opens the comparison preview window for the selected image.
`⌘` + `O`	Add Images...	Choose files or folders to add to the list.
`⌘` + `V`	Add Images from Clipboard	Adds image files you copied in Finder to the list.
`⌘` + `A`	Select All	Selects every file in the list.
`⌘` + `⌫`	Clear Images	Removes the selected images from the list (the original files aren't deleted).
`⌘` + `F`	Search...	Shows a search field for filtering the list.
`⇧` + `⌘` + `W`	Open Watermark...	Opens the Watermark window.
`⌘` + `1` – `9`	Switch preset	Switches to saved presets 1–9 (empty slots can't be chosen).
`⌘` + `0`	None (no preset)	Unlinks the current preset. Your current settings stay as they are.
`⌘` + `,`	Settings...	Opens the Settings window.
`⌘` + `←` / `→`	Show or hide sidebars	Shows or hides the status sidebar on the left and the settings sidebar on the right.
`↑` / `↓`	Move the selection	Moves the selection up or down in the list (hold `⇧` to extend it).
`esc`	Deselect	Clears the selection (or closes the search field if it's open).

Preview window

Shortcut	Command	Description
`⌘` + `R`	Reconvert	Converts the displayed image again.
`⌘` + `S`	Save	Saves the converted result as a file.
`⌘` + `C` / `⌘` + `D`	Copy as File / Copy as Data	Copies the converted result to the clipboard.
`⌘` + `I`	Show image metadata	Overlays color, HDR, and EXIF information for both the original and the converted image.
`Space`	Toggle full view	Switches between showing only the converted image and only the original.
`←` / `→`	Previous / next image	Moves to the previous or next image in the list.
`⌘` + `←` / `→`	Move the slider to an edge	Moves the slider all the way to the left or right.
`⌘` + `=` / `⌘` + `-`	Zoom in / out	Zooms the view in or out. `⌘` + `0` resets the zoom.
`esc`	Reset the view	Resets the zoom and the slider position.
`⌘` + `W`	Close	Closes the preview window.

FAQ

Frequently Asked Questions

Answers to common questions about image conversion and settings.

Q. Should I use WebP or AVIF for my website?

WebP works in every modern browser (Safari, Chrome, Firefox, Edge) and has the widest compatibility, so it's the first choice.
AVIF has the edge when you want even smaller files or need to deliver 10-bit HDR.

Q. Can a converted file end up larger than the original?

It can, for example when an already heavily compressed JPEG is re-encoded as lossy WebP at a high quality (90 or above). Turn on Save only if file size is reduced under Output Conditions in the Input / Output section, and files that don't get smaller won't be saved (it's off by default).

Q. Could my original files be overwritten or lost?

You can save to the same folder as the originals (Save in Original Image's Folder), to a folder you choose, or pick a folder each time (Select Output Folder when Starting). No folder is chosen at first, so the app asks for one the first time you convert. If a file with the same name already exists, the new file is saved under a numbered name, so with the default settings your originals are never lost.
However, if you turn on Overwrite existing images and save in the same format to the same folder, the original is overwritten. And if you turn on Trash original images under Post-conversion, the originals are moved to the Trash.