Image Formats
When editing images in Photoshop, there are a number of choices about which image format to save in, or export to. It’s important to understand the different image formats and the differences that will apply to editing images.
Every file on a computer has a filename, then a period (full stop), then a file extension. This is usually 3 letters, but can be more, e.g. .jpg, .psd, .docx. The file extension tells the computer what type of file, each file is.
Quick Summary of Common Image Formats (for more information, see below).
- JPEG, JPG - Default format for phones and cameras. Universal. Compressed.
- PSD - Default Photoshop format. I recommend it. It preserves everything you do in Photoshop.
- RAW - file extension varies, according to camera make. Raw files are best for the ultimate image quality, but require time, software and expertise to edit.
- DNG - Adobe’s raw format
- PNG - Useful for images where you want a transparent background, typically for the web.
- TIFF, TIF - A popular and much used format and it is compatible with Photoshop and layers. I generally prefer the Photoshop PSD format because it produces a smaller filesize than the TIFF format, which is approximately 24% larger based on my non-scientific comparisons on several images.
- WEBP - Smaller filesize at a similar quality to jpeg, so ideal for websites. Also supports transparency, like png.
Note that this is not an exhaustive list of image formats. It is intended to list common formats that a beginner to Photoshop, should be aware of.
Image Formats Explained
.jpeg .jpg
Images taken on phones are almost always saved in jpeg format. Images taken on cameras can be saved in jpeg, raw, or both simultaneously.
It’s useful to be aware of the following, with jpeg images.
- All Jpeg images are compressed. This is very handy for minimizing filesize. The more they are compressed, the smaller the filesize, but the lower the quality.
- Photoshop Layers are not supported in jpegs.
- Repeated saving in jpeg format will gradually lose quality (like repeatedly photocopying a photocopy).
- When a photo is taken in jpeg format, either on a phone or a camera, the image is processed in the phone or camera with various settings, such as; sharpness, saturation, contrast, colour temperature, colour tone.
Jpeg images are compressed
Every jpeg image is compressed. This happens in your camera or phone when you take the image.
Compression keeps the filesize small, which is convenient, so you can save more images on your phone or memory card. It's also useful to keep images small, to share with friends and family. But there is a sacrifice of image quality, although when using WhatsApp and similar app's, this is insignificant.
If you open a jpeg image in Photoshop and edit it, then save it as a jpeg image, you will have a choice of quality settings. Higher quality means less compression and will result in a larger file. Lower quality settings result in smaller files, but more loss of quality. If you repeatedly save a jpeg, while working on it, the image quality will gradually degrade (at all quality settings, but faster at the lower quality settings). This is like taking a photocopy of a photocopy. At first you won’t see much, if any, difference, but after a while you will.
When you save in jpeg format you will lose all Photoshop layers
In Photoshop, if your image has several layers, but you save it as a jpeg file, all your visible layers will be compressed into one layer and you will permanently lose access to individual layers (unless you also save the layered file as either .PSD or .TIFF. Layers that are not visible will be ignored and lost. Proceed at this point with caution. If you have spent any time working on an image, it’s usually best to save the image in Photoshop format first, which will preserve all layers and then again in jpeg format, (see below).
Each time you save a jpeg image you lose quality
If jpeg images are repeatedly saved, a little quality is lost each time, although at the highest quality settings you won’t see much difference after a few saves. When you save a jpeg file you have a choice of quality setting, usually 1-12, or 1-10. The higher the number, the better the quality, the less it is compressed and the file size is larger. The lower the quality, the more it is compressed to achieve a smaller file size and the more it loses quality.
If all you want to do is open an original jpeg image and make a few changes, such as brightness and contrast, it’s fine to save the image in its jpeg format (preferably just saving once). Noticeable loss of quality occurs when saving an image many times, especially at a low quality setting. A low resolution image will degrade faster.
For email or website use, choose a lower quality setting for a smaller filesize, but if quality is important, I recommend saving at maximum quality.
Jpeg images are processed in camera
Each time you take a jpeg image, your camera processes various settings to achieve the end result you see. These settings include;
- White Balance / Colour Temperature, e.g. sunny, cloudy, artificial light.
- Contrast
- Sharpening
- Colour Tone
- Monochrome
- Highlight Priority
You can change these settings in your camera, if you choose to shoot jpeg images. Please refer to your camera manual for details on how to do this.
Photoshop PSD Format
The Photoshop format is PSD, which is short for Photoshop Document.
When you first open an image into Photoshop, it could be from a jpeg, raw, Photoshop or other format. At that point it makes no difference, but what happens after that is important.
As you work on an image, perhaps adding layers, layer masks, layer styles, text and more, it is important to save your work, to be able return to it later.
The Photoshop PSD format is an ideal format for working on images in Photoshop, as it will preserve all layers, layer masks, etc. When you save an image for the first time in Photoshop, if you have added any additional layers, Photoshop will automatically select the PSD format to save the file. This is ideal and I recommend it.
Good editing practice should be done in a way that preserves the original, so you can always revert to that. If you save an edited image as a PSD file, you will preserve the original jpeg.
If you are a beginner and are editing a jpeg in Photoshop, I recommend creating a duplicate layer and editing that layer. As you progress you will learn about other methods that don’t require a duplicate layer, yet still preserve your image. After adding at least one layer, when saving for the first time, Photoshop will automatically offer to save it as a Photoshop .psd format image (psd = Photoshop Document). You should always do this to preserve your layers. Remember, its good practice to edit on a different layer.
Tip: When saving in Photoshop .psd format, leave the file name unchanged. Filenames have to be unique, but the file extension, (3 or 4 letters after the full stop in the filename), will change from jpg to psd, thus preserving unique filenames. In the future, months or years later, you can easily see which files are from the same image, which can be very useful.
Saving it in the Photoshop format will save all layers in your image and will ensure you can save it as many times as you like without losing any quality.
Saving a jpeg version from a Photoshop .psd file
- Save in Photoshop .psd format. Make sure you have saved any changes before saving in the jpeg format.
- Select File > Save As. In the format option box, select jpeg.
- Append the filename i.e. with a number, or letter, to preserve your original jpeg image.
- All jpeg images are compressed, so when saving, select an appropriate quality setting. For best quality, select the highest number. This will compress the image the least, but retain the best quality.
If you leave the filename unchanged and you save in the same folder as the original jpeg, it will be replaced by your edited image.
Raw Format
Most, if not all, cameras will allow you to choose between shooting images in jpeg, raw, or both formats simultaneously. At the time of writing phones will tend to just shoot jpegs, although this could change in the future.
Raw images are not processed in the camera. They are later processed with your choices in appropriate software, such as Lightroom, or software that came with your camera.
A raw image contains much more data than a jpeg and is therefore larger. For example, a jpeg image contains 256 tones between black and white in each of the three colors; red, green and blue. A 12bit raw image contains 4096 tones and a 14bit raw image contains 16,384 tones between black and white in each colour. Because of the extra data that the raw file contains, you can achieve a higher quality image. An example of where this is useful would be a landscape image with a bright sky. A jpeg image could lose detail in the brightest areas of the sky, whereas a raw image could retain that detail.
Because raw images are larger, it means that you can fit less raw images on a memory card, than jpeg images. Memory cards are so large nowadays and relatively inexpensive, that I don’t think that should be a concern. The same applies to hard disks.
If you use Lightroom, there some superb tools, such as Denoise, only work on raw images. They won’t work at all on jpeg images.
Note that raw files can’t be edited directly, so they automatically preserve the original (even if edited in Lightroom, or opened into Photoshop).When a raw file is edited in Lightroom, the edited settings are saved either in a separate “sidecar” file, or within the raw file itself. The original raw file cannot be changed.
Shooting raw or jpeg is a choice. Raw files gives you greater flexibility compared to jpeg files, but there is nothing wrong, or inferior if you choose to just shoot jpeg. You will have to be very careful with exposure.
Raw vs Jpeg Comparison - Which is better?
One advantage of a raw file over a jpeg is retaining detail in highlights (the lightest areas in a photo), that would otherwise be “blown out”, (lost), for example in an image with high contrast and a very bright sky.
A raw image retains the detail, which can be brought out in editing, whilst retaining a natural look.
See Raw vs Jpg Comparison for a comparison of the advantages of editing a raw image vs a jpg image.
DNG
DNG is shorthand for Digital Negative. Each camera manufacturer, such as Canon, Nikon, Sony, all have their own proprietary raw formats, which require specific software to edit them.
The DNG format was created by Adobe, to provide photographers with a standardized format for RAW files that is not tied to proprietary formats from camera manufacturers, (which may become obsolete over time).
However, there is a possibility that some of the original, proprietary RAW data may be lost or altered. Some tools in Lightroom will not currently work on DNG files; they need the original RAW files. An example of an excellent Lightroom tool is Denoise (which miraculously reduces digital noise on high ISO images, shot in low light). It may be that in the future, this tool (and other tools) may work with DNG files.
You can convert your original RAW files into the DNG format, using the free Adobe app, DNG Converter. When converting you can select either Lossless or Lossy. Lossless does not compress the file, whereas Lossy does compress the file (approximately the same as saving as a jpeg at maximum quality).
Whilst I recognize that the DNG format is useful and has the best of intentions, I would advise that you keep your RAW files in the original format. Some of Lightroom’s tools only work on the original RAW format, (such as the excellent DeNoise). Who knows what new tools will appear in the future. Of course, it may be that Adobe add functionality to enable new tools to work on the .dng format, but history has shown that this lags behind support for proprietary raw formats.
PNG
PNG is shorthand for Portable Network Graphic, which is a type of raster image file (pixels). Unlike the jpeg format, it supports transparent or semi-transparent backgrounds. It’s usually used with graphic designs, but can be used with photos. Jpeg does not support transparent backgrounds.
TIFF, TIF
Tif, or Tiff, is shorthand for Tagged Image File Format. A number of people recommend TIF over PSD, and there are some advantages, but in my experience, it comes with an increased filesize of (sometimes 24% or more), so for the majority, I would suggest sticking with PSD files, as I do. But either is fine to save layered files.
WEBP
This is a relatively new format, and perhaps should not be included here, but if you are creating images for websites, you should be aware of this. This format is fully supported in the major browsers (Chrome, Edge, Firefox, Opera). It’s quality is comparable to jpeg, but at much smaller filesize. This is ideal for websites (most of the images on this site are in the .webp format).
