I read an article today about image file formats and it seems there is much confusion about the properties, advantages, and disadvantages of image file formats. RAW, TIFF, PNG, GIF, JPEG are the most common, I would like to pass on what I have learned and make some suggestions to make the photographers’ decisions easier.
First there is the concept of color space. Your eyes see the world in multiple colors and each cone or cell in the retina records the color that it absorbs in technically a 3-coordinate color. The eye can perceive around 10 million colors (haven’t seen a crayon box with that many colors, lol). The objective of the photographer is to record as many of these colors as possible.
So, when you shoot an image with your digital camera, each pixel records only one color in a 3-coordinate value. Remember camera sensors are rated in how many pixels are on the sensor, i.e. 10, 20, 30, 40, 50 million pixels or megapixels on the sensor. Then the millions of pixels combine to give you an image.
When you shoot in RAW, the camera sensor records the exact color exposed on each pixel. The problem with RAW is you need software that can read that type of image format like Lightroom, Photoshop, Elements, etc. RAW images then need to be saved in some type of image format that then can be viewed by regular image viewing software.
The image format most are familiar with is jpeg. Jpegs are great for sending electronically because they have the smallest file size. But this size comes at a cost. Jpegs are called “lossy compression” because they are manipulated to reduce their size and data is lost. You can view jpegs on most viewing software and are good to view on computer screens, tablets, and phones. Another issue with processing jpegs is every time you open a jpeg in photo editing software, you compress it once more when saving thus losing data. Also, jpegs are in an 8- bit format which means a maximum of 256 colors. This sounds adequate and is when viewing electronically.
BUT…..printing can give much more color. A simple 4 color CMYK printer can produce up to 16,000 colors, way more than the 8-bit 256. You can easily see that if you print a jpeg, you lose some of the advantages of what a print can give you.
TIFF files are huge but contain the most information. This information can be transferred to a printed image. 16-bit TIFF files can maintain 65,536 tonal ranges with 281 trillion colors. The data advantage is enormous. Yes, these files are huge, but computer storage is CHEAP! One of the reasons TIFFs are so large is they contain all the color coordinates per pixel and can have the larger 16-bit depth.
PNG (Portable Network Graphics) file format is used by Adobe and other editing programs and are stored if a LOSSLESS compression thus have a reduced file size. PNGs are used widely in computer graphics. PNGs have much more information than jpegs but less than TIFFs.
So how do you want to record and store your images? First of all, always shoot in RAW and keep your RAW images (storage is cheap). After processing, you can use multiple image formats when saving. Saving in TIFF has a large file size, but you can always go back to it with all the data preserved. TIFF files offer the most information for printing and should be used for fine art prints.
One of the biggest disadvantages of TIFFs is the files are usually larger than what email attachments allow. When using a printing service, use one that you can upload a large, 16-bit TIFF file. If the service only supports jpeg, you will lose some of the advantage a print can give you. This means that the service has to have some type of file transfer program, i.e. you upload your file.
If you are sending an image or using social media, the viewer will be using a computer monitor, tablet, or phone. This is a small format compared to a print and you will not see the quality difference. So when viewing electronically, jpegs are fine and even superior due to their small file size.
In conclusion, save your processed image in TIFF to retain maximum data. When printing try and use TIFF. Make a separate jpeg to send via email or when posting to systems that will be viewed electronically.
Hope this helps.