iPhone - comparing jpeg, heif, and raw images

Photos of a tin taken with iPhone 15 pro at 2x magnification

The industry standard since 1992 has been the JPEG, a file format that allows large files to be compressed into smaller sizes.  The problem with jpegs is that they are lossy, meaning that the compression algorithm causes changes in the pixel patterns of the image.  The more compression, the more severe the artifacts.  Examine the image below to see an example of artifacts.

In 2015 HEIF files were introduced and have been a popular file format in smart phones.  They are lossless, meaning that there are not artifacts, and is typically a better format for your camera images.  They are also fairly small; the JPEG above (using a compression ratio of 8:1) is about twice as large as the HEIF.  

One of the problems with the HEIF format is that many computers cannot open them.  Mac computers all are equipped with the necessary software, but PCs (and probably Linex) do not have it.  However, you can buy conversion software that will change your HEIF file into something accessible.  When I opened the HEIF file from my phone with Photoshop, it opened as a TIFF file, another lossless file format.  However, TIFF files are huge.  The HEIF image took up only 1.85 mb, while the TIFF uncompressed version too up 69.8 mb, about 38x the size of the parent image.

If you get a TIFF image from your HEIF, convert it to a low-compression JPEG or keep it as a HEIF if possible.

My iPhone 15 Pro also allows me to save the image as a RAW file using Adobe's DNG (digital negative) format.  However, instead of using 8 bits per channel (b/c) the image was encrypted with 16 b/c.  This does use more memory, but it also allows the user to produce more accurate prints.  Not many programs can work in 16 bit colour and so you may need to change it to 8 bit, something JPEGS and HEIFs use.

The main advantage of the RAW file type is that you can alter many of the file's characteristics in a non-destructive way and obtain greater latitude than what either JPEGs or HEIFs can do.  I only shoot RAW on my DSLRs and mirrorless cameras, but on my iPhone I will probably use the HEIF format in order to keep file sizes down and quality up.

If you want files that require the least amount of work, have no need for translation, and produce very acceptable images, use the JPEG format (usually says "most compatible" in control panels).  If you want the best images you can with the least amount of memory used, choose the HEIF format.  And for those of you who want the absolute best file type without caring about memory or compatibility with software, go for the RAW.  Keep in mind that most cell phones allow you to choose JPEG or HEIF while RAW may not be an option.

Thanks for reading.

Eric Svendsen     www.ericspix.com

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