1. In the native format of their program. This will keep all layers intact in case you ever need to go back and change anything (names, typos, photos, etc).
This means that if you want a file that keeps the layers to work with it needs to be a ".PSD" file which is a Photoshop working file.

2. As a high resolution (200-300 ppi - ppi = pixels per inch) JPG for easy printing. For this option, merge all layers, choose "save as" and then save as a JPG with very little compression.

3. As a low resolution (72ppi) JPG for the web. 432 pixels tall is a good size for easy screen viewing.. You can adjust the compression to make your image under 125K, which is the limit on most websites.

.BMP's or Bitmaps

BMP files are an historic (but still commonly used) file format for the historic (but still commonly used) operating system called "Windows". BMP images can range from black and white (1 bit per pixel) up to 24 bit colour (16.7 million colours). While the images can be compressed, this is rarely used in practice

In uncompressed BMP files, and many other bitmap file formats, image pixels are stored with a color depth of 1, 4, 8, 16, 24, or 32 bits per pixel.

Uncompressed formats are generally unsuitable for transferring images on the Internet or other slow or capacity-limited media.

Saving GIF Files in Photoshop

A common problem in Adobe Photoshop (and Image Ready) is being unable to save a file in the GIF format. This can happen:

When saving a normal Photoshop file
When using the "Save Optimised As" option
When using the "Save for Web" option
... and possibly other situations as well

"Save As..."

If you are trying to use the "Save As" command but there is no GIF option in the format drop-menu, then you are using the wrong image mode. In the file menu go to Image > Mode and change the mode to RGB or Indexed Color. Now try saving again — you should see GIF amongst the options.

"Save For Web"

In the Save For Web window, look at the options on the right hand side. Make sure the format drop-menu is set to GIF. If it's not, you will only be able to save the file in an RGB format such as JPG.

Image Ready

If you are trying to use the "Save Optimised As" option in Image Ready you may find a similar problem with a similar solution. Open your "Optimize" palette (Window > Optimize) and make sure it is set to GIF.

Photoshop 'Save for Web' options

More about Optomizing & Saving GIFs

JPG Options

This is where we compress the JPG file.

The compression option usually appears when you save a JPG image, although it may not be labelled as such. You will usually see a window which says something like "JPEG Options" or "Image Quality". Typically this will include a sliding scale, perhaps 1 to 10 or 0% to 100%. If you save the image and this option doesn't appear, try selecting "Save As" and saving with a different file name. If you still don't get the option, consult the program's help file and search for "compression" or "image quality".

The higher the selected image quality, the larger the file size. The key is to find the lowest setting which retains an acceptable quality. We recommend saving several versions with different compression settings. Then starting with he smallest file, look at each one and choose the first file which is acceptable quality.

Note: When altering the compression setting, the change may not be apparent until you open the file next time.

Image Quality Example

The close-up image below has been saved with three different compression settings, with 12 being the highest quality and 0 the lowest.

As you can see, the drop from 12 to 3 has reduced the file size by almost 50% with no significant degradation. You will also notice the drop from 3 to 0 degrades the image a lot, but hasn't reduced the file size much further. At this point the trade-off is no longer worth it so we would normally stick with the 13KB version.


Quality: 12 File Size: 23K	Quality: 3 File Size: 13K	Quality: 0 File Size: 12K

The original version of this photo was 2048x1536 pixels. Reducing the quality setting from 10 to 3 drops the file size dramatically - from 966KB to 276KB.

Summary

It's always a good idea to save the original version of a file separately.
Use JPG for files with lots of colours, use GIF for files with fewer colours.
Use the lowest image quality setting you can get away with.
When altering the compression setting, the change may not be apparent until you open the file next time.
Be careful about making consecutive changes to a file, eg don't reduce then enlarge an image - use "undo" instead.

FAQ

I try to convert an image to a different format but my program won't let me.
Some formats can't be converted directly to certain other formats. Try converting the image to the "RGB" format (it will be one of the options), then to the format you need.

My program won't let me save as a GIF
This can happen if the image has more than 256 colours. You need to change the file mode to "Indexed Colour" - consult your program's help file to find out how to do this.

When I upload an image to my website it doesn't work.
Assuming your file is a JPG or GIF, the cause is most likely an HTML error in the web page rather than a problem with the image file.

How do I save an image from a website?
Go to the web page, right-click the image and select "Save Image As..." (or whatever equivalent option your browser uses). Make sure you have permission to do so - otherwise it's theft.

How can I create a snapshot of the display on my computer monitor?
Use your keyboard's "Print Screen" button. This is like taking a photo of the current display on your monitor and copying it to your clipboard. Open your graphics program and create a new file. If necessary, specify the size of the new file as "current clipboard". Then select "Paste" and the snapshot is inserted into the file for you to edit and save. This simple method is how we created the Photoshop 7 screenshots for this tutorial.

Note: If pressing the "Print Screen" key doesn't work, try holding down the "Alt" key while you press "Print Screen".

File Formats
There are many different file formats to save your photos and your pages in.
.PSD	Photoshop's native format. Will keep layers intact. Can also be opened by PSP and PI.
.PSP	Paint Shop Pro's native format. Will keep layers intact.
.UFO	Photoimpact's native format. Will keep layers intact.
.PNG Plus	DIP's native format. Will keep layers intact and can also be opened as a regular PNG by other programs but with no layers.
.PNG	File format used to retain the transparency of an item. Most digital embellishments come in this format.
. JPG	A lossy-format for saving graphic files. Widely used because of its small file size. JPGs sacrifice resolution for file size. Every time a JPG is re-saved it compresses again and you lose resolution. It is like making a photocopy of a photocopy. If you need to resave a JPG make sure you do a "save-as" and name it something new.
. BMP	A lossy-format for saving graphic files. Widely used because of its file size
.TIFF	.A non-lossy format for saving graphic files. Very large file size though