To JPEG

JPEG uses lossy compression optimized for photographs and smooth color gradients. Unlike PNG, JPEG does not support transparency—transparent areas render with a solid background.

import Foundation
import IMGLYEngine

@MainActor
func toJpeg(engine: Engine) async throws {
  let assetsBase = "https://cdn.img.ly/packages/imgly/cesdk-swift/1.75.1/assets"
  try engine.editor.setSettingString("basePath", value: assetsBase)
  let sceneURL = URL(string: "\(assetsBase)/ly.img.template/templates/cesdk_postcard_1.scene")!
  try await engine.scene.load(from: sceneURL)

  let page = try engine.scene.getPages().first!

  let blob: Blob = try await engine.block.export(
    page,
    mimeType: .jpeg,
    options: ExportOptions(jpegQuality: 0.9),
  )

  let highQualityBlob = try await engine.block.export(
    page,
    mimeType: .jpeg,
    options: ExportOptions(jpegQuality: 1.0),
  )

  let sizedBlob = try await engine.block.export(
    page,
    mimeType: .jpeg,
    options: ExportOptions(
      jpegQuality: 0.85,
      targetWidth: 1920,
      targetHeight: 1080,
    ),
  )

  let outputURL = FileManager.default.temporaryDirectory.appendingPathComponent("export.jpg")
  try blob.write(to: outputURL)

  _ = highQualityBlob
  _ = sizedBlob
}

This guide covers exporting to JPEG, configuring quality and dimensions, and saving exports to disk.

Export to JPEG#

Export a design block by calling engine.block.export(_:mimeType:options:) with .jpeg as the MIME type. The call returns a Blob (a Data value) containing the encoded image.

let blob: Blob = try await engine.block.export(
  page,
  mimeType: .jpeg,
  options: ExportOptions(jpegQuality: 0.9),
)

The jpegQuality parameter accepts values from greater than 0 to 1. Higher values produce better quality at larger file sizes. The default is 0.9.

Export Options#

JPEG export reads these fields from ExportOptions:

mimeType is the second argument to engine.block.export(_:mimeType:options:), not a field on ExportOptions.

Quality Control#

Set jpegQuality to 1.0 for maximum quality with minimal compression artifacts. This is useful for archival or print preparation.

let highQualityBlob = try await engine.block.export(
  page,
  mimeType: .jpeg,
  options: ExportOptions(jpegQuality: 1.0),
)

For web delivery, values around 0.8 balance quality and file size effectively.

Target Dimensions#

Specify targetWidth and targetHeight to export at exact dimensions. The output fills the target size while maintaining aspect ratio.

let sizedBlob = try await engine.block.export(
  page,
  mimeType: .jpeg,
  options: ExportOptions(
    jpegQuality: 0.85,
    targetWidth: 1920,
    targetHeight: 1080,
  ),
)

Save to File System#

The returned Blob is a Data value, so writing it to disk is a single call to write(to:).

let outputURL = FileManager.default.temporaryDirectory.appendingPathComponent("export.jpg")
try blob.write(to: outputURL)

When to Use JPEG#

JPEG works well for:

• Photographs and images with gradual color transitions
• Social media posts and web content
• Scenarios where file size matters more than perfect quality

Troubleshooting#

Output looks blurry — Increase jpegQuality toward 1.0, or use PNG for graphics with hard edges.

File size too large — Decrease jpegQuality to 0.7–0.8, or reduce dimensions with targetWidth and targetHeight.

Unexpected background — JPEG does not support transparency. Use PNG or WebP for transparent content.

API Reference#

Next Steps#

• Export Overview — Compare all available export formats
• Export to PDF — Export for print and document workflows
• Partial Export — Learn how to export specific blocks, groups, and page elements instead of entire scenes using CE.SDK’s programmatic export API.
• Create Thumbnail — Generate thumbnail preview images by exporting with target dimensions