jpegmeta

package
v1.8.21 Latest Latest
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 Go to latest Published: Apr 3, 2026 License: MIT Imports: 9 Imported by: 0

Documentation

Overview

Package jpegmeta provides support for working with embedded JPEG metadata.

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

func ExtractMetadata 

func ExtractMetadata(r io.Reader) (md *meta.Data, err error)

Same as Load() except that no new stream is provided

func Load 

func Load(r io.Reader) (md *meta.Data, imgStream io.Reader, err error)

Load loads the metadata for a JPEG image stream.

Only as much of the stream is consumed as necessary to extract the metadata; the returned stream contains a buffered copy of the consumed data such that reading from it will produce the same results as fully reading the input stream. This provides a convenient way to load the full image after loading the metadata.

Example (BaselineJPEGMetadata) 
package main

import (
	"fmt"
	"github.com/kovidgoyal/imaging/prism/meta"
	"github.com/kovidgoyal/imaging/prism/meta/jpegmeta"
	"image"
	"image/jpeg"
	"os"
)

func printMetadata(md *meta.Data, img image.Image) {
	fmt.Printf("Format: %s\n", md.Format)
	fmt.Printf("BitsPerComponent: %d\n", md.BitsPerComponent)
	fmt.Printf("PixelHeight: %d\n", md.PixelHeight)
	fmt.Printf("PixelWidth: %d\n", md.PixelWidth)

	fmt.Printf("Actual image height: %d\n", img.Bounds().Dy())
	fmt.Printf("Actual image width: %d\n", img.Bounds().Dx())
}

func main() {
	inFile, err := os.Open("../../test-images/pizza-rgb8-srgb.jpg")
	if err != nil {
		panic(err)
	}
	defer inFile.Close()

	md, imgStream, err := jpegmeta.Load(inFile)
	if err != nil {
		panic(err)
	}

	img, err := jpeg.Decode(imgStream)
	if err != nil {
		panic(err)
	}

	printMetadata(md, img)

}

Output:
Format: JPEG
BitsPerComponent: 8
PixelHeight: 1200
PixelWidth: 1200
Actual image height: 1200
Actual image width: 1200
Example (EmbeddedICCv2) 
package main

import (
	"fmt"
	"github.com/kovidgoyal/imaging/prism/meta"
	"github.com/kovidgoyal/imaging/prism/meta/jpegmeta"
	"image/jpeg"
	"os"
)

func printICCProfile(md *meta.Data) {
	profile, err := md.ICCProfile()
	if err != nil {
		panic(err)
	}

	fmt.Printf("ProfileSize: %d\n", profile.Header.ProfileSize)
	fmt.Printf("PreferredCMM: %v\n", profile.Header.PreferredCMM)
	fmt.Printf("ProfileVersion: %s\n", profile.Header.Version)
	fmt.Printf("DeviceClass: %s\n", profile.Header.DeviceClass)
	fmt.Printf("DataColorSpace: %s\n", profile.Header.DataColorSpace)
	fmt.Printf("PCS: %s\n", profile.Header.ProfileConnectionSpace)
	fmt.Printf("CreatedAt: %v\n", profile.Header.CreatedAt())
	fmt.Printf("PrimaryPlatform: %v\n", profile.Header.PrimaryPlatform)
	fmt.Printf("Embedded: %v\n", profile.Header.Embedded())
	fmt.Printf("DependsOnEmbeddedData: %v\n", profile.Header.DependsOnEmbeddedData())
	fmt.Printf("DeviceManufacturer: %s\n", profile.Header.DeviceManufacturer)
	fmt.Printf("DeviceModel: %s\n", profile.Header.DeviceModel)
	fmt.Printf("DeviceAttributes: %064b\n", profile.Header.DeviceAttributes)
	fmt.Printf("RenderingIntent: %v\n", profile.Header.RenderingIntent)
	fmt.Printf("PCSIlluminant: %v\n", profile.Header.PCSIlluminant)
	fmt.Printf("ProfileCreator: %v\n", profile.Header.ProfileCreator)
	fmt.Printf("ProfileID: %0x\n", profile.Header.ProfileID)

	if desc, err := profile.Description(); err != nil {
		panic(err)
	} else {
		fmt.Printf("Description: %s\n", desc)
	}
}

func main() {
	inFile, err := os.Open("../../test-images/pizza-rgb8-adobergb.jpg")
	if err != nil {
		panic(err)
	}
	defer inFile.Close()

	md, imgStream, err := jpegmeta.Load(inFile)
	if err != nil {
		panic(err)
	}

	_, err = jpeg.Decode(imgStream)
	if err != nil {
		panic(err)
	}

	printICCProfile(md)

}

Output:
ProfileSize: 596
PreferredCMM: 'lcms'
ProfileVersion: 2.1.0
DeviceClass: Display
DataColorSpace: RGB
PCS: XYZ
CreatedAt: 2000-08-11 19:51:59 +0000 UTC
PrimaryPlatform: Apple Computer, Inc.
Embedded: false
DependsOnEmbeddedData: false
DeviceManufacturer: 'none'
DeviceModel: '    '
DeviceAttributes: 0000000000000000000000000000000000000000000000000000000000000000
RenderingIntent: Perceptual
PCSIlluminant: [0 0 246 214 0 1 0 0 0 0 211 45]
ProfileCreator: 'lcms'
ProfileID: 00000000000000000000000000000000
Description: Adobe RGB (1998)
Example (EmbeddedICCv4) 
package main

import (
	"fmt"
	"github.com/kovidgoyal/imaging/prism/meta"
	"github.com/kovidgoyal/imaging/prism/meta/jpegmeta"
	"image/jpeg"
	"os"
)

func printICCProfile(md *meta.Data) {
	profile, err := md.ICCProfile()
	if err != nil {
		panic(err)
	}

	fmt.Printf("ProfileSize: %d\n", profile.Header.ProfileSize)
	fmt.Printf("PreferredCMM: %v\n", profile.Header.PreferredCMM)
	fmt.Printf("ProfileVersion: %s\n", profile.Header.Version)
	fmt.Printf("DeviceClass: %s\n", profile.Header.DeviceClass)
	fmt.Printf("DataColorSpace: %s\n", profile.Header.DataColorSpace)
	fmt.Printf("PCS: %s\n", profile.Header.ProfileConnectionSpace)
	fmt.Printf("CreatedAt: %v\n", profile.Header.CreatedAt())
	fmt.Printf("PrimaryPlatform: %v\n", profile.Header.PrimaryPlatform)
	fmt.Printf("Embedded: %v\n", profile.Header.Embedded())
	fmt.Printf("DependsOnEmbeddedData: %v\n", profile.Header.DependsOnEmbeddedData())
	fmt.Printf("DeviceManufacturer: %s\n", profile.Header.DeviceManufacturer)
	fmt.Printf("DeviceModel: %s\n", profile.Header.DeviceModel)
	fmt.Printf("DeviceAttributes: %064b\n", profile.Header.DeviceAttributes)
	fmt.Printf("RenderingIntent: %v\n", profile.Header.RenderingIntent)
	fmt.Printf("PCSIlluminant: %v\n", profile.Header.PCSIlluminant)
	fmt.Printf("ProfileCreator: %v\n", profile.Header.ProfileCreator)
	fmt.Printf("ProfileID: %0x\n", profile.Header.ProfileID)

	if desc, err := profile.Description(); err != nil {
		panic(err)
	} else {
		fmt.Printf("Description: %s\n", desc)
	}
}

func main() {
	inFile, err := os.Open("../../test-images/pizza-rgb8-srgb.jpg")
	if err != nil {
		panic(err)
	}
	defer inFile.Close()

	md, imgStream, err := jpegmeta.Load(inFile)
	if err != nil {
		panic(err)
	}

	_, err = jpeg.Decode(imgStream)
	if err != nil {
		panic(err)
	}

	printICCProfile(md)

}

Output:
ProfileSize: 596
PreferredCMM: 'lcms'
ProfileVersion: 4.3.0
DeviceClass: Display
DataColorSpace: RGB
PCS: XYZ
CreatedAt: 2020-07-27 09:09:41 +0000 UTC
PrimaryPlatform: Apple Computer, Inc.
Embedded: false
DependsOnEmbeddedData: false
DeviceManufacturer: '    '
DeviceModel: '    '
DeviceAttributes: 0000000000000000000000000000000000000000000000000000000000000000
RenderingIntent: Perceptual
PCSIlluminant: [0 0 246 214 0 1 0 0 0 0 211 45]
ProfileCreator: 'lcms'
ProfileID: 00000000000000000000000000000000
Description: sRGB IEC61966-2.1
Example (EmbeddedICCv4WithNullLanguageCountry) 
package main

import (
	"fmt"
	"github.com/kovidgoyal/imaging/prism/meta"
	"github.com/kovidgoyal/imaging/prism/meta/jpegmeta"
	"image/jpeg"
	"os"
)

func printICCProfile(md *meta.Data) {
	profile, err := md.ICCProfile()
	if err != nil {
		panic(err)
	}

	fmt.Printf("ProfileSize: %d\n", profile.Header.ProfileSize)
	fmt.Printf("PreferredCMM: %v\n", profile.Header.PreferredCMM)
	fmt.Printf("ProfileVersion: %s\n", profile.Header.Version)
	fmt.Printf("DeviceClass: %s\n", profile.Header.DeviceClass)
	fmt.Printf("DataColorSpace: %s\n", profile.Header.DataColorSpace)
	fmt.Printf("PCS: %s\n", profile.Header.ProfileConnectionSpace)
	fmt.Printf("CreatedAt: %v\n", profile.Header.CreatedAt())
	fmt.Printf("PrimaryPlatform: %v\n", profile.Header.PrimaryPlatform)
	fmt.Printf("Embedded: %v\n", profile.Header.Embedded())
	fmt.Printf("DependsOnEmbeddedData: %v\n", profile.Header.DependsOnEmbeddedData())
	fmt.Printf("DeviceManufacturer: %s\n", profile.Header.DeviceManufacturer)
	fmt.Printf("DeviceModel: %s\n", profile.Header.DeviceModel)
	fmt.Printf("DeviceAttributes: %064b\n", profile.Header.DeviceAttributes)
	fmt.Printf("RenderingIntent: %v\n", profile.Header.RenderingIntent)
	fmt.Printf("PCSIlluminant: %v\n", profile.Header.PCSIlluminant)
	fmt.Printf("ProfileCreator: %v\n", profile.Header.ProfileCreator)
	fmt.Printf("ProfileID: %0x\n", profile.Header.ProfileID)

	if desc, err := profile.Description(); err != nil {
		panic(err)
	} else {
		fmt.Printf("Description: %s\n", desc)
	}
}

func main() {
	inFile, err := os.Open("../../test-images/pizza-rgb8-displayp3.jpg")
	if err != nil {
		panic(err)
	}
	defer inFile.Close()

	md, imgStream, err := jpegmeta.Load(inFile)
	if err != nil {
		panic(err)
	}

	_, err = jpeg.Decode(imgStream)
	if err != nil {
		panic(err)
	}

	printICCProfile(md)

}

Output:
ProfileSize: 492
PreferredCMM: 'lcms'
ProfileVersion: 4.0.0
DeviceClass: Display
DataColorSpace: RGB
PCS: XYZ
CreatedAt: 2017-07-07 13:22:32 +0000 UTC
PrimaryPlatform: Apple Computer, Inc.
Embedded: false
DependsOnEmbeddedData: false
DeviceManufacturer: 'APPL'
DeviceModel: '    '
DeviceAttributes: 0000000000000000000000000000000000000000000000000000000000000000
RenderingIntent: Perceptual
PCSIlluminant: [0 0 246 214 0 1 0 0 0 0 211 45]
ProfileCreator: 'lcms'
ProfileID: ca1a9582257f104d389913d5d1ea1582
Description: Display P3
Example (ProgressiveJPEGMetadata) 
package main

import (
	"fmt"
	"github.com/kovidgoyal/imaging/prism/meta"
	"github.com/kovidgoyal/imaging/prism/meta/jpegmeta"
	"image"
	"image/jpeg"
	"os"
)

func printMetadata(md *meta.Data, img image.Image) {
	fmt.Printf("Format: %s\n", md.Format)
	fmt.Printf("BitsPerComponent: %d\n", md.BitsPerComponent)
	fmt.Printf("PixelHeight: %d\n", md.PixelHeight)
	fmt.Printf("PixelWidth: %d\n", md.PixelWidth)

	fmt.Printf("Actual image height: %d\n", img.Bounds().Dy())
	fmt.Printf("Actual image width: %d\n", img.Bounds().Dx())
}

func main() {
	inFile, err := os.Open("../../test-images/pizza-progressive.jpg")
	if err != nil {
		panic(err)
	}
	defer inFile.Close()

	md, imgStream, err := jpegmeta.Load(inFile)
	if err != nil {
		panic(err)
	}

	img, err := jpeg.Decode(imgStream)
	if err != nil {
		panic(err)
	}

	printMetadata(md, img)

}

Output:
Format: JPEG
BitsPerComponent: 8
PixelHeight: 1200
PixelWidth: 1200
Actual image height: 1200
Actual image width: 1200

func NewSegmentReader 

func NewSegmentReader(r io.Reader) *segmentReader

Types

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