If you’ve ever used Photoshop a slight bit, you have seen the quite large list of file types you can export an image as. Today, I want to quickly demystify what they are and which has the best quality-to-file size ratio. I’ll only cover the standard file types that are available in the Save As box when exporting a PSD. As my methodology, I’ll open a final Photoshop document from a recent shoot, convert it to sRGB (so that if some do not support anything better, we can still perform a fair comparison), resize it to 3000 px on the longest side and extract the file’s weight and a 200% zoom screenshot to judge the quality. All file formats that support lossless compression are set to it. I’ll also do a super breezy description of the format’s characteristic. All right, let’s start!

 

PSD (Original)

File Size: 80.1MB

Stands For: Photoshop Document

Description: It’s the default file format that Photoshop exports. It can save every elements of a file (layer mask, transparency, various color spaces, alpha channels, etc…) but is limited to a size of 2GB or side length of 30 000 pixels. This is the best it’s going to get as far as IQ (Image Quality) so it’s the benchmark for right now. Large Document Format (PSB, for Photoshop Big) is exactly the same but supports up to 300 000 pixels per side and a maximum file size of about 4 Exabytes (4 billions GB).

Cineon

File Size: 29.2MB

Description: The Cineon file format is part of the Cineon system. It was developed by Kodak and consisted of a way to digitally manipulate film negatives. It’s not commonly used these days. What’s surprising about it is that it is still a high fidelity, high resolution and small size file format but was conceived more than 20 years ago.

Dicom

File Size: 19.4MB

Stands For: Digital Imaging and Communications in Medicine

Description: The file format is used in medicine to facilitate the distribution and viewing of medical scans such as fMRIs, CT sounds and ultrasound. It was developed by the NEMA (National Electrical Manufacturers Association). What is unique about the file format is that is has a way to records the patient’s information, image size, type of scan, etc. right in. The file supports 3D images.

IFF Format

File Size: 30.4MB

Stands For: Interchange File Format

Description: Created by Electronic Arts (EA) in 1985, and aiming to facilitate file sharing between softwares from different operating systems and platforms, it is a universal format that can contain anything from images and audio to text, games and more. It’s long dead but still manages to stay around by some way. The file size tops at 4GB, which was quite respectable 30 years ago. To put some perspective on that, the Mac, which was release in early 1984, had a 400KB floppy disk.

JPEG

File Size: 1.7MB

Stands For: Joint Photographic Experts Group

Description: That is a very important file format. It’s characterised by it’s (usually) tiny size, not-so-great IQ and insane wide adoption. Something to note is that it’s mainly used for photographs with gradients as opposed to graphics with sharp colours cutoff because the quality really takes a hit in the latter. Also, the less complicated an area of your image is (smaller number of colours, simpler patterns, monochromatic, etc…) the less data is going to required. That’s a characteristic of the compression algorithm of JPEG. The web runs on it because of it’s support of the small colour space sRGB, it’s small file size and complete support by everything. There’s a lot to learn about JPEG.

JPEG 2000

File Size: 12.8MB

Stands For: Joint Photographic Experts Group 2000

Description: It is the same as JPEG but better. Let me explain. While the regular .jpg file format was introduced in 1992, this one saw the light of day in 2000. It brings several improvements over the first iteration, including the support for lossless compression, transparency, better compression performance, more bit depth (16- and 32-bit floating point), more colour spaces and other. Although it is better in pretty much every aspect than it’s older brother, we still mostly use usual JPEG. The file extension is .jpf. The screenshot above is from a lossless JPEG 2000 image so no visible quality degradation should be observed.

JPEG Stereo

JPEGStereo.png

File Size: 1.7MB

Stands For: Joint Photographic Experts Group Stereo

Description: You know those fake 3D images where the actual photo is duplicated and one is red and the other blue? That’s what JPEG Stereo is. It is based on, well, JPEG and has the .jps extension. It may be useful to know that the file can only be opened by a few 3D programs. It’s not really used and there is not a lot of discussion about it online.

Multi-Picture Format

File Size: 1.7MB

Description: .MP is yet again another file format derived from JPEG. It keeps the file size down. It is also another technique to do 3D with JPEG files. For example, the web browser on a Nintendo 3DS is able to understand those file and give a better 3D feeling than JPEG Stereo.

Photoshop PDF

Stands For: Photoshop Portable Document Format

File Size: 1.8MB (though that depends greatly on the settings you choose)

Description: This is your standard PDF file. However, it does have the option to preserve layer-related infos from Ps, such as alphas channels, notes, spot colours, etc…. There’s a slew of settings you can tinker with in the Save Adobe PDF section that comes after the Save As dialog box.

Photoshop RAW

File Size: 43.8MB

Description: Just like DNG (Digital Negative), the Photoshop RAW format will keep all of the pixels intact with no degradation (hence, RAW). However, unlike DNG (and pretty much all other files), it does not keep a “header” with the file’s info (for example, its dimensions). That means that you need to enter them manually before opening the file or else you’ll get funky results. It does not conserve any layer-related info and is not much used. You NEED to write down the file’s properties of else it’s going to render unusable.

PNG

File Size: 58.5MB

Stands For: Portable Network Graphic

Description: I would label this one as JPEG’s biggest opponent. It is not as widely used but can brag that it is almost the first file format that people choose when they want to conserve some transparency. Furthermore, PNG has the ability to be compress losslessly and it is the most used file format on the Internet that’s lossless. It was created to replace the aging (but still fun) GIFs (Graphic Interchange Format) files. Compared to JPEG, PNG almost always yields bigger (but with more IQ) results.

Portable Bit Map

Portable Bit Map.png

File Size: 43.8MB

Description: Portable Bit Map (.pbm) files aim to be the simplest of them all. That would mean a lot of compatibility. Unfortunately, the file format is almost useless. It supports up to 24-bit (which is higher than most professional DSLR’s RAW files). There’s not much to say about it other than I’d try not to use that particular one.

TIFF

File Size: 102.3MB

Stands For: Tagged Image File Format

Description: TIFF is widely used by photographers and graphic artists as it is very much supported and can offer lossless images. Most commercial product photographers that export files from, let’s say, Capture One Pro, to work on them in Ps use that file format. The downside to it is the huge file size. The other advantages of it however are that it can keep layer informations just like a PSD file and some pretty advanced compression methods to reduce the file size when the top quality isn’t needed. TIFF is actually older than JPEG (released in 1986) and has not seen any major updates since 1992.

Seeing those results made me realise how much of a versatile program Photoshop is. We don’t think of it but it’s utilized in a lot industries such as medicine, architecture, photography, graphic design, publishing, fashion design, etc…. Adobe has a web page about who uses Photoshop. We can see that most lossless image format turn around the 40 to 70 MB range whereas the lossy ones tend to go at about 1 to 10 MB. I wonder why there is no file size of 30MB (of course, these numbers are for my particular image). That would probably mean crappy compression algorithms.

I’d say that JPEG has the overall size-to-quality ratio. At 100% quality (not lossless though) and a file size of 1.7MB, it really does some good job. Plus, it’s extremely widely used. A new BPG file format promises the same quality as JPEG but in a much smaller package. That could be cool but it’s not yet implemented.

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Cheers,

Tristan