Whats A Dmg

Overview Information. Dimethylglycine is an amino acid, a building block for protein. It is found in the body in very small amounts and for only seconds at a time. People use dimethylglycine to make medicine. Dimethylglycine is used for attention deficit-hyperactivity disorder ( ADHD ), epilepsy, chronic fatigue syndrome ( CFS ), allergies. DMG-01 is the model number of the original grey Gameboy and the later 'Play It Loud!' Series, which used the same hardware just in different colored cases. DMG stands for.

Should you use DNG or RAW format? This is one of the most important questions that you as a photographer need to ask yourself, because it will definitely affect your digital photography workflow. Every photographer has their own say on whether to use DNG or RAW, but it is important to know the key differences between the two, along with their advantages and disadvantages. In this article, I will provide as much information as I can about both formats, in addition to my opinion and workflow. If you are looking for more information about how RAW images compare to JPEG images, then please read my “RAW vs JPEG” article.

1. What is RAW?

RAW images, also known as “digital negatives” are truly “raw”, meaning they are almost unprocessed data coming directly from the camera sensor. Unlike JPEG files that can be easily opened, viewed and printed by most image-viewing/editing programs, RAW is a proprietary format that is tied to the camera manufacturer and sensor, and therefore is not supported by all software products. RAW files preserve the most amount of information about an image and generally contain more colors and dynamic range than other formats.

1.1. Advantages of RAW Format

1. RAW files contain full JPEG Previews that were processed by the camera, using the camera settings you chose when you shot the image.
2. In addition to basic exposure information, RAW files also store other camera-specific data such as focus point, picture controls, etc.
3. RAW files are fully supported by their manufacturers and therefore work with camera-specific software packages such as Nikon Capture NX.

1.2. Disadvantages of RAW format

1. Not all software packages can open RAW files. If you have a brand new camera that just got released, you might need to wait for a while for software companies to catch up and update their software so that your RAW files could be opened and worked on, even on the most popular image-editing products such as Lightroom.
2. Because RAW files cannot be modified by third party software, your settings will have to be stored in a separate sidecar (XMP) file, which means more storage and tougher file management.

2. What is DNG?

DNG is also considered to be a RAW image file. It is Adobe’s proprietary image standard that was created to store image data in a generic, highly-compatible format, unlike RAW files that have specific formats based on manufacturer and camera type. Although DNG was invented by Adobe and is supported in all Adobe applications, there are other camera manufacturers such as Leica, Hasselblad and Pentax that adopted this standard and use it in their cameras as their native and supported RAW file format.

2.1. What are the Advantages of DNG format?

1. No need to be worried about proprietary camera RAW formats – once a RAW file in converted to DNG, it will work with any software that can properly read the DNG format.
2. DNG files can be made smaller than RAW files if minimal or no JPEG Preview is stored within the file.
3. Changes to images can be written directly into DNG files without having to create separate sidecar XMP files to store this data. This simplifies file management.
4. DNG files are capable of storing full original RAW files and these RAW files can be later be manually extracted, if needed (note: this will significantly increase DNG file size).
5. Adobe provides many ways to automatically convert RAW images to DNG format in such programs as Lightroom.
6. Unlike RAW files, the DNG format includes checksum information in the file to detect and prevent file corruption.
7. Adobe continues to work on the DNG format, enhancing it year after year and adding more functionality and features.

2.2. What are the Disadvantages of DNG format?

1. Conversion from RAW to DNG takes extra time during the import process. This can be significant when converting high-resolution images.
2. DNG does not work with most manufacturer image-processing programs. For example, it doesn’t work with Nikon’s Capture NX software.
3. DNG strips out most of the unrecognized meta data (such as Active D-Lighting, Picture Controls, Focus Point, etc) from RAW files, making it impossible to retrieve this data from DNG in the future.
4. Because all changes are written into the DNG file, you need to back up the entire DNG file every time you make changes to it.

3. Should You Use DNG or RAW?

There was a time in the past when I used to convert all of my images from RAW to DNG format. I stopped this practice after a few years, because I realized that DNG was not becoming a wide standard among all manufacturers and it was not as open and documented as I thought it would be. Most software other than Adobe’s had issues reading the DNG format and the loss of some potentially important metadata was not something I was comfortable with. I wrote my thoughts in a comprehensive article titled “Why I No Longer Convert RAW Files to DNG” and I recommend that you give it a read, since there is quite a bit of information there.

What Is A Dmg Contribution Fee

Please let me know if you have any questions or feedback in the comments section below.

Apple Disk Image is a disk image format commonly used by the macOS operating system. When opened, an Apple Disk Image is mounted as a volume within the Macintosh Finder.

An Apple Disk Image can be structured according to one of several proprietary disk image formats, including the Universal Disk Image Format (UDIF) and the New Disk Image Format (NDIF). An Apple disk image file's name usually has '.dmg' as its extension.

• 3File format

Features[edit]

Apple Disk Image files are published with a MIME type of application/x-apple-diskimage.

Different file systems can be contained inside these disk images, and there is also support for creating hybrid optical media images that contain multiple file systems.^[1] Some of the file systems supported include Hierarchical File System (HFS), HFS Plus, File Allocation Table (FAT), ISO9660 and Universal Disk Format (UDF).^[1][2]

Apple Disk Images can be created using utilities bundled with Mac OS X, specifically Disk Copy in Mac OS X v10.2 and earlier and Disk Utility in Mac OS X v10.3 and later. These utilities can also use Apple disk image files as images for burning CDs and DVDs. Disk image files may also be managed via the command line interface using the hdiutil utility.^[3]

In Mac OS X v10.2.3, Apple introduced Compressed Disk Images^[4] and Internet-Enabled Disk Images for use with the Apple utility Disk Copy, which was later integrated into Disk Utility in 10.3. The Disk Copy application had the ability to display a multi-lingual software license agreement before mounting a disk image. The image will not be mounted unless the user indicates agreement with the license.^[5]

An Apple Disk Image allows secure password protection as well as file compression, and hence serves both security and file distribution functions; such a disk image is most commonly used to distribute software over the Internet.

History[edit]

Apple originally created its disk image formats because the resource fork used by Mac applications could not easily be transferred over mixed networks such as those that make up the Internet. Even as the use of resource forks declined with Mac OS X, disk images remained the standard software distribution format. Disk images allow the distributor to control the Finder's presentation of the window, which is commonly used to instruct the user to copy the application to the correct folder.

A previous version of the format, intended only for floppy disk images, is usually referred to as 'Disk Copy 4.2' format, after the version of the Disk Copy utility that was used to handle these images.^[1] A similar format that supported compression of floppy disk images is called DART.^[1][6]

New Disk Image Format (NDIF) was the previous default disk image format in Mac OS 9,^[1] and disk images with this format generally have a .img (not to be confused with raw .img disk image files) or .smi file extension. Files with the .smi extension are actually applications that mount an embedded disk image, thus a 'Self Mounting Image', and are intended only for Mac OS 9 and earlier.^[7][2]

Universal Disk Image Format (UDIF) is the native disk image format for Mac OS X. Disk images in this format typically have a .dmg extension.^[1]

File format[edit]

Apple has not released any documentation on the format, but attempts to reverse engineer parts of the format have been successful. The encrypted layer was reverse engineered in an implementation called VileFault^[8] (a spoonerism of FileVault).

Apple disk image files are essentially raw disk images (i.e. contain block data) with some added metadata, optionally with one or two layers applied that provide compression and encryption. In hdiutil these layers are called CUDIFEncoding and CEncryptedEncoding.^[1]

UDIF supports ADC (an old proprietary compression format by Apple), zlib, bzip2 (as of Mac OS X v10.4), and LZFSE (as of Mac OS X v10.11)^[9] compression internally.

Trailer[edit]

The trailer can be described using the following C structure.^[10] All values are big-endian (PowerPC byte ordering)

Here is an explanation:

Utilities[edit]

There are few options available to extract files or mount the proprietary Apple Disk Image format. Some cross-platform conversion utilities are:

• dmg2img was originally written in Perl; however, the Perl version is no longer maintained, and the project was rewritten in C. Currently, without additional tools, the resulting images may be mounted only under Mac OS X and under Linux (provided hfsplus support has been enabled). UDIF ADC-compressed images have been supported since version 1.5.^[11]
• DMGEXtractor is written in Java with GUI, and it supports more advanced features of dmg including AES-128 encrypted images but not UDCO images.^[12]
• 7-Zip, including the free cross-platform port of its command-line interface, p7zip.

In Windows, most dmg images can be opened using several other programs such as UltraISO and IsoBuster. MacDrive can also mount simple dmg files as drives under windows, but not sparse disk or encrypted dmgs.^[13] A free Apple DMG Disk Image Viewer also exists.^[14]

In Linux and possibly other Unix flavors, most .dmg files can be burned to CD/DVD using any CD-burner program (using cdrecord directly or a front-end such as K3B or Brasero) or directly mounted to a mountpoint (e.g. mount -o loop,ro -t hfsplus imagefile.dmg /mnt/mountpoint).^[15][16] darling-dmg is a FUSE module enabling easy DMG file mounting on Linux.^[17]

See also[edit]

References[edit]

1. ^ ^abcdefg'hdiutil(1) Mac OS X Manual Page'. Archived from the original on 2016-05-14. Retrieved 2016-05-14.
2. ^ ^ab'Mac OS X: Using Disk Copy disk image files'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
3. ^hdiutil(1) – Darwin and macOS General Commands Manual
4. ^'Re: Some apps refuse to launch in 10.2.8! (OT, but very important)'. Archived from the original on 2014-01-17.
5. ^'Guides'. Apple. Archived from the original on 2009-03-06. Retrieved 2010-10-27.
6. ^'DART 1.5.3: Version Change History'. Archived from the original on 2013-12-19. Retrieved 2013-04-25.
7. ^'Software Downloads: Formats and Common Error Messages'. Archived from the original on 2010-12-24. Retrieved 2009-05-06.
8. ^'VileFault'. 2006-12-29. Archived from the original on 2007-01-09. Retrieved 2010-10-27.
9. ^Michael Tsai (2015-10-07). 'LZFSE Disk Images in El Capitan'. Archived from the original on 2017-04-09. Retrieved 2017-04-09.
10. ^'Demystifying the DMG File Format'. Archived from the original on 2013-03-17.
11. ^'dmg2img'. Archived from the original on 29 November 2010. Retrieved 2010-10-27.
12. ^'DMGExtractor'. Archived from the original on 2011-01-02. Retrieved 2011-01-03.
13. ^MacDrive Features / Boot Camp / System Requirements /. 'MacDrive Home page'. Mediafour. Archived from the original on 4 October 2010. Retrieved 2010-10-27.
14. ^Olivia Dehaviland (2015-03-03). 'Apple DMG Disk Image Viewer'. DataForensics.org. Archived from the original on 2015-04-02. Retrieved 2015-03-10.
15. ^'How To Convert DMG To ISO in Windows, Linux & Mac'. Archived from the original on 2010-03-07.
16. ^'Convert DMG To ISO using PowerISO'. Archived from the original on 2009-05-02. Retrieved 2009-02-15.
17. ^'darling-dmg'. darling-dmg. Retrieved 29 March 2015.

External links[edit]

• Apple Developer Connection A Quick Look at PackageMaker and Installer
• O'Reilly Mac DevCenter Tip 16-5. Create a Disk Image from a Directory in the Terminal

What Is A Dmg Image