Background Images

Image Options and Accessible Descriptions

Deckset interprets the text inside ![...] as image options. Use alt(...) to add an accessible description to an informative image:

![fit informative alt(Diagram showing the product workflow)](workflow.jpg)

Use decorative when the image does not add information that assistive technologies need to convey:

![decorative](texture.jpg)

Background images without alt(...) are treated as decorative automatically, but adding decorative makes that intent explicit. Quoted text is not an accessible description: use alt(Description) instead of "Description".

Full Background Image

![decorative](image1.jpg)

Fit Background Image

![fit decorative](image1.jpg)

Multiple Background Images

![decorative](image1.jpg)
![decorative](image2.jpg)
![decorative](image3.jpg)

Text on Images

![decorative](image2.jpg)

# Text on Images

Setting text on images applies a filter to the image to make the text more readable.

Disable Filter

![original decorative](image2.jpg)

# Disable Filter

Zoom In

![original 250% decorative](image2.jpg)

# Zoom In

Split Slides

![left alt(Photograph accompanying the slide)](image1.jpg)

# Split Slides

Use the `left` or `right` modifiers to place the image in the left or right half of the slide, respectively.

Adjust Filters

![left filtered alt(Photograph with the theme filter applied)](image1.jpg)

# Force Apply Filter

Use the `filtered` keyword to apply the theme's filter to an image that isn't filtered by default.

Built-in Image Modifiers

![left bn alt(Black-and-white photograph)](image1.jpg)
![right vivid alt(Vivid photograph)](image2.jpg)
![left noir alt(Noir photograph)](image1.jpg)
![right chrome alt(Chrome-effect photograph)](image2.jpg)
![left fade alt(Faded photograph)](image1.jpg)

Use bn (or bw) for black-and-white, vivid for boosted color/contrast, and noir/chrome/fade for Core Image photo effect presets.

These modifiers replace the theme filter for that specific image.

Saturation

![left saturation(0.6) alt(Desaturated photograph)](image1.jpg)
![right vivid saturation(0.9) alt(Vivid photograph with adjusted saturation)](image2.jpg)

Use saturation(value) to set saturation directly (0...2, clamped).
When combined with bn or vivid, explicit saturation(...) wins for saturation.

Composable Filters

![left sepia(0.7) vignette(0.5) alt(Sepia photograph with a dark vignette)](image1.jpg)
![right vignette(-0.5) blur(0.35) contrast(1.2) alt(Blurred high-contrast photograph)](image2.jpg)

Mix and match filters freely. Deckset applies them in a consistent order, so you always get the same result. Positive vignette(...) values darken the edges. Negative values lighten them.

Additional supported controls include:

• blur(0...1)
• contrast(0...2)
• brightness(-1...1)
• exposure(-2...2)
• vignette(-1...1)
• sepia(0...1)
• sharpen(0...1)

Split Slides with Fit

![right fit alt(Photograph fitted into the right side of the slide)](image2.jpg)

# Split Slides

Combine `left` or `right` with the `fit` keyword or a percentage to adjust the image scaling.

Alpha

Use alpha on an image to specify its opacity.

![right alpha(0.6) alt(Semi-transparent photograph)](image2.jpg)

Global Background Image

To apply a background image to every slide in your presentation, simply add the background-image command at the very top of your Markdown file:

background-image: image2.jpg

(rest of your content)

If a background image conveys information, add an alt(...) description and mark it informative. Background images without descriptions are treated as decorative during accessible export. See Accessible Media.