---
canonical: https://amplience.com/developers/docs/apis/media-delivery/media-delivery-reference/format-and-quality/
title: Format and quality
  interactive: true
description: Control Dynamic Media output format and compression with the Amplience Media Delivery API, including fmt, fmt=auto, quality settings, DPI, metadata stripping, and JPEG and PNG options.
keywords:
  - Dynamic Media
  - Media Delivery API
  - Dynamic Media image format
  - fmt auto
  - WebP
  - AVIF
  - image quality
  - image compression
audience: Developer
date_published: 2026-07-12
date_modified: 2026-07-27
---

# Format and quality {#format-and-quality}

The Media Delivery API lets you set the output format explicitly, or let `fmt=auto` serve the best format each browser supports. Compression can be set for a single request, per format, or left to the defaults configured for your account.

> **Note: Base URL pattern**
> The parameters on this page are appended to a Dynamic Media image URL. For the URL pattern and how parameters chain together, see the [Media Delivery API guide](https://amplience.com/developers/docs/apis/media-delivery/media-delivery-reference/).

> **Info: Verifying format and quality changes**
> Most parameters in this section change the encoded file rather than its on-screen appearance, so an interactive preview would look identical before and after. To verify them, open the generated URL in a new tab and check the response `Content-Type` header and transfer size in your browser's developer tools (Network tab). For more detail on how to find this information, see the [Amplience Smart Images example](https://amplience.com/developers/docs/dev-tools/guides-tutorials/media-delivery/smart-image/#amplience-smart-images-example).

## `qlt` — Quality {#qlt}

Sets the compression quality as a percentage (0–100). JPEG is lossy; PNG is lossless but zlib-compressed.

This example pins `fmt=jpg` and a 500px output so compression artefacts are visible at preview size. Switch the format to `png` and the image stops changing - on PNG output, `qlt` affects file size but not appearance.

```uri
https://cdn.media.amplience.net/i/ampproduct/woman-checked-skirt-striped-bag?w=500&fmt=jpg&qlt=80
```

## `fmt` — Output format {#fmt}

Sets the output format. If not specified, the format matches the original. Setting the image file extension also changes the format.

Supported values: `jpg`, `png`, `gif`, `bmp`, `webp`, `avif`, `jp2`

> **Note:** - `webp` is not supported in all browsers. See [browser support](https://caniuse.com/#feat=webp).
> - `jp2` is supported in Safari for iOS and macOS only.
> - `avif` requires [Accelerated Media](https://amplience.com/developers/docs/apis/media-delivery/media-delivery-reference/#accelerated-media). Images larger than 2.5 megapixels fall back to `jpeg` (or `png` if transparency is present).

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/woman-checked-skirt-striped-bag?fmt=png
```

## `fmt=auto` — Auto format {#fmt-auto}

Returns the image in the most efficient format supported by the requesting browser.

> **Info:** This feature, and `avif` support, requires [Accelerated Media](https://amplience.com/developers/docs/apis/media-delivery/media-delivery-reference/#accelerated-media).

Format selection priority:

1. `avif` - if enabled on your account and [supported by the browser](https://caniuse.com/?search=avif)
2. `webp` - for Safari, Chrome, Firefox and other browsers that support it
3. `jp2` - for Safari versions that support `jp2` but not `webp`
4. `jpg` - fallback for all other browsers
5. `png` - if the original image contains transparency and the browser is Safari

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/women-bright-colors.jpg?fmt=auto
```

For more information, see [Amplience Smart Images](https://amplience.com/developers/docs/dev-tools/guides-tutorials/media-delivery/smart-image).

## `qlt=default` — Default format quality {#qlt-default}

Applies the platform default quality setting for the output format. Can be combined with `fmt=auto`.

Default quality values by format:

| Format | Default quality |
|---|---|
| `jp2` | 40 |
| `avif` | 55 |
| `webp` | 80 |
| `jpeg` | 75 |
| `png` | 90 |

Custom defaults can be set in your account root template or transformation templates.

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/women-bright-colors.jpg?fmt=auto&qlt=default
```

## Per-format quality parameters {#per-format-quality}

Sets the compression quality for a specific output format. Can be combined with `fmt=auto`.

| Parameter | Format |
|---|---|
| `fmt.avif.qlt` | AVIF |
| `fmt.webp.qlt` | WebP |
| `fmt.jp2.qlt` | JPEG 2000 |
| `fmt.jpeg.qlt` | JPEG |
| `fmt.png.qlt` | PNG |

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/women-bright-colors.jpg?fmt=auto&fmt.webp.qlt=50
```

## `dpi` - Dots per inch {#dpi}

Changes the image resolution. If not specified, the image is returned at its original DPI.

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/signature-hat-german?dpi=120&w=200
```

## `dpiFilter` - DPI resampling algorithm {#dpifilter}

Specifies the resampling algorithm used when the DPI is changed.

| Value | Description |
|---|---|
| `q` | Quadratic |
| `s` | Sinc |
| `l` | Lanczos (default) |
| `p` | Point |
| `c` | Cubic |

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/signature-hat-german?dpi=120&dpiFilter=q&w=200
```

## `strip` - Strip metadata {#strip}

Removes commands and metadata from the image. Accepts `true` or `false`. Default is `false`.

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/woman-checked-skirt-striped-bag?strip=true
```

## `fmt.jpeg.chroma` - Chroma subsampling {#fmt-jpeg-chroma}

Controls JPEG chroma subsampling, which reduces file size by sampling colour at a lower rate than brightness.

| Value | Description |
|---|---|
| `2,1,1` | Enabled (default) |
| `1,1,1` | Disabled |

Disabling chroma subsampling increases file size; consider reducing `qlt` to compensate.

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/woman-checked-skirt-striped-bag?fmt=jpg&fmt.jpeg.chroma=1,1,1
```

## `fmt.jpeg.interlaced` - Progressive JPEG {#fmt-jpeg-interlaced}

Add `fmt.jpeg.interlaced=true` to a JPEG URL to return the image as a progressive JPEG. Progressive JPEGs load a low-quality version of the whole image first and refine it as more data downloads, rather than rendering top-to-bottom.

The effect is only observable while the file is downloading - on a fast connection the image simply appears complete, so there is nothing useful to preview here. To see it in action, apply the parameter to a large JPEG and load it with network throttling enabled in your browser's developer tools.

See the [progressive images](https://amplience.com/developers/docs/dev-tools/guides-tutorials/media-delivery/progressive-images) guide for more information.

## PNG output options {#png-output-options}

Control how PNG output is encoded. All three parameters affect file size rather than on-screen appearance.

| Parameter | Values | Description |
|---|---|---|
| `fmt.png.indexed` | `true` / `false` | Use an indexed colour palette rather than per-pixel colour data. Default: `false`. |
| `fmt.png.palettesize` | 1–256 | Colour palette size for indexed PNGs. Requires `fmt.png.indexed=true`. Default: `256`. |
| `fmt.png.dither` | `true` / `false` | Dithering for indexed PNGs. Smooths colour banding but may slightly increase file size. Default: `true`. |

**Example:**

```uri
https://cdn.media.amplience.net/i/ampproduct/woman-checked-skirt-striped-bag?fmt=png&fmt.png.indexed=true&fmt.png.palettesize=256&fmt.png.dither=true
```