Understanding the Basics - A Guide to Common Image File Formats in Photography
“I’m not a technical photographer, and I try to keep things as simple as possible.” - Annie Leibovitz
The ability to effectively create with digital photography lies in file formats. However, understanding formats, like many other topics in photography, can be complex and technical. As a photographer and educator, I prefer to keep things simple.
JPEG
The JPEG, or Joint Photographic Experts Group format, has been around since 1992. JPEGs can display over 16 million colors. It is also a compressible file that reduces storage space and is the format ideal for web viewing and social media. JPEG is also the standard format for many native camera apps. While the JPEG will most likely be around for a while longer, it has some limitations in quality and editability.
JPEG images are compressed, which is what reduces storage space. Because of this, some information contained within the image is destroyed. Are you old enough to ever have dubbed a cassette tape? If so, you might remember that the copy had a slightly lower quality than the original. And if you made a copy of the copy, it got even fuzzier. JPEGs work similarly. The image is initially compressed once it is created. If the image is uploaded to social media, it is compressed again. Then what if you decide to download and save that image on your phone? Yep, it is compressed again. Each subsequent compression results in a loss of quality and becomes noticeable.
These characteristics are essential to remember when it comes to editing JPEGs. An analogy I heard several years ago sums it up best. When editing your photos, think of the JPEG like baking a cake. When it is processed, it’s baked. You can put it back in the oven a bit longer if it isn’t cooked enough. However, what happens if you burn the cake?
When camera software processes an image, it determines the best values for sharpness, color, exposure, contrast, and an array of other adjustments. Therefore, think of taking pictures in a JPEG format like trying to fix an already cooked, or worse, a burned cake. You can always put it back in and make cook it more, but there is no way to revert any damage.
HEIF
The High Efficiency Image Format, or HEIF, could one day replace the JPEG. HEIF offers many of the benefits of a JPEG and then some; however, HEIF is a lossless compression format. In other words, unlike the information that is lost when a JPEG is created, HEIF files maintain their integrity. They also have the same benefit of using less space as their JPEG cousin but offer far greater color rendition.
The downside is that not many applications can run HEIF files (sometimes seen as .HEIC extensions). The format has become native to Apple devices, and some Windows-based devices can read HEIF files. However, you may be required to download an additional program to open the file. Some social media outlets state they accept HEIF files but often convert them to JPEG.
TIFF
Tagged Image File Format, or TIFF, is a lossless uncompressed format. While it is a processed format, it contains the highest resolution while maintaining image detail and integrity. Outside of cell phones, not many camera manufacturers can take photos in TIFF format. However, file sizes are much larger, and images can be layered or stacked together. Layering allows for creating images that contain a greater depth of color and multiple layers of editing adjustments.
Many printing and publishing companies use TIFF or JPEG formats for the final product. In terms of size comparison, a processed high-quality JPEG image can yield a 9MB to 30MB file, whereas the same uncompressed TIFF image can be two or three times that size. While TIFF files are great for preserving image quality, they also suffer from the same editing woes as JPEGs, and TIFFs are ideal for converting and saving a final image after editing.
RAW
The best option for taking photos is in a RAW format. RAW files are unprocessed, and it does not represent an acronym. RAW files are a data file meaning no image is recorded. So what’s the big deal about RAW? A RAW file gives you the greatest flexibility in editing your photos and ensures you capture the highest quality image.
Until recently, it was almost impossible to take photos in a RAW format on a cell phone without a third-party app; however, nearly all DSLR and mirrorless cameras can record RAW image files. Software is needed to view RAW files, which converts them to something we can see. This includes in-camera software or computer-based programs such as Lightroom.
RAW is a generic term, and manufacturers often use their own file extensions. For example, Nikon is .NEF, Canon is .CRW, and Sony is .ARW. While the file extensions are not universal among manufacturers, the concept is the same – a digital, uncompressed, and unprocessed file. Once the image is processed, it can be saved as a file extension, such as .JPEG or .TIFF.
You will notice stark differences if you compare a RAW file next to a processed image. Most manufacturer RAW files also yield a different appearance from one to the next. For example, one may have more color or contrast than another. Often a viewable RAW file is drab, appears to lack color, and sometimes they are effectively referred to as being almost black and white. This is because no image processing has taken place, and minimal values are applied for settings such as color, hue, and contrast.
Behind the scenes, DSLRs, mirrorless, and cell phone cameras take image data in RAW. However, the image you see on the screen is temporarily processed and not the final product unless you are saving it as a JPEG or another format. The camera’s software processes a viewable preview image, and you will find RAW file looks a little different on the computer. A universal RAW file extension is .DNG, or Digital Negative. Because this format is universal, it works well with cell phones.
RAW files are like an unbaked cake with almost endless possibilities. You can cook it just right or burn it, and the best part, you can undo it and start over. RAW formats allow you the greatest flexibility when it comes to editing, being creative, and making your photos look like your vision.
HDR – The Other Format
High Dynamic Range, or HDR, is not new, but it is often available as a high-quality image option. Cameras are limited in the range of light they can process, and it is not near the level of what the human eye can detect. A camera can capture between five to seven stops of light for a given image, while the human eye can detect as many as twenty. Think of a stop of light as changes in shading.
Imagine a color chart with pure white on one end and absolute black on the other. Computer screens can display up to 256 different shades of grey between the white and black values, while the human eye can distinguish over 500. Now pick a point on either scale and count five to seven spaces away in either direction. That is the range your camera can effectively capture light. Now do the same thing but count twenty spaces to visualize how our eyes capture light differently. The purpose of capturing HDR images is to produce photos that have similar ranges of contrast (light and dark) that are closer to the human eye.
Shades of Light
HDR is a process where multiple images of varying contrast are combined to help increase that image’s dynamic range. Each camera manufacturer has a different method regarding how they achieve this process. For example, some cameras take three pictures, often two JPEGs and one RAW, and combine them. Some applications take and combine up to five images. Each manufacturer determines the final output file extension; however, it is often .JPEG, .HDR, or .TIFF.
You can also create an HDR image by using a technique called bracketing. In this instance, you take as many photos as you like. The camera remains stationary, and the only thing that changes is the exposure value. You end up with a flipbook of sorts, but rather than capturing changes in motion, you have captured changes in shades of light. However, it will take a program such as Lightroom or Photoshop to combine and align the images into a final HDR product.
While HDR is a great resource, it is better suited for landscape photography and has no real application in portraits. Often HDR processing can make an image appear less realistic and almost cartoonish when applied to some scenes where it is not needed.
The Importance of Understanding Formats
Why are formats important? Beyond how your camera saves an image, file formats dictate how much data we use in saving a given image, but more importantly, they can unlock the ability to edit. If you are a photographer only interested in capturing a particular moment, formats may not be important. However, understanding common file types is essential if you want the ability to edit and unlock your creative potential.
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