Let's go over how to set up your image files. From a technical standpoint, you will most likely use Adobe Photoshop and/or Adobe Illustrator to create and enhance your actual graphics. Please refer to the step on hardware & software if you don't have these programs. Later, we will go over how to place and position your images onto each page with text. But for now we will focus on preparing the actual image files separately.
Keep your digital files organized from the beginning.
If you want to avoid headaches later on, I recommend you use consistent file naming and utilize folders on your computer to stay digitally organized. Keep all of your image files collected in 1 or more clearly-labelled folders. Set the names of files and folders so you can remember what they are. Name them based on what they look like, what page # they go on, or however is useful to you. If every file is named "untitled" you will get confused quickly. You are taking the time to create a book, so treat your files & documents with care. They should be well preserved if you want to reprint again in the future.
Don't change what comes after the .(period) in a file name.
As stated, you should name your files but always leave the text after the period unchanged. This is the file type extension and it tells us and the computer what kind of file it is. The extension should not be changed unless a program is changing the file. For example if you have a file called picture.jpg, the JPG is the file type extension, telling us the image is in "Joint Photographic Experts Group" format. You do not want to change or remove .jpg. Only a program that can handle the file should change it's format. If you opened picture.jpg in Photoshop and selected "Save As..." to save a new version of it in another format, Photoshop will change the extension for you. There is rarely a need for you to manually change a file's extension. If you change it yourself, it may break the file.
Images come in many formats.
As mentioned, the letters after the .period in a file name tell you what type of format the file is. There are thousands of computer file formats out there. A few hundred of them are specifically for images. I suggest keeping life simple and working with only a few I will go over below.
Common image file formats and how they are different:
PSD: Adobe Photoshop's native file format. It can contain raster images, layers, text, and effects. PSDs play nicely with InDesign. If your images are in this format, you can drop them right into your InDesign page layout without changing them to another format. This format does not lose quality and can have transparency.|
AI: Adobe Illustrator's native file format. It can contain vector graphics, layers, text, and effects. AIs play nicely with InDesign. If your graphics are in this format, you can drop them right into your InDesign page layout without changing them to another format. This format does not lose quality and can have transparency.
TIFF: a universal format recommended for most images and graphics. It is ideal because it does not lose quality when you save, it can have transparency, layers, and many programs can open TIFFs.
PNG: a great format for images and graphics on screen, but not printed. It does not lose quality when you save, it can have transparency, and many programs can open PNGs. The only limitation is that a PNG cannot be in CMYK color format, which is what we need for our printed book. TIFF format is better for print images.
JPG: this format is for raster images and graphics, but is not the best format to choose. The problem with JPG format is they lose a small amount of image quality every time you save them, degrading the image over time. They also cannot have transparency. If you have JPG images to work with, I would recommended you convert them in a graphics program (like Photoshop) to TIFF format.
Color settings for all graphics should be set to CMYK.
If you have graphics that are set up in RGB color mode, the final printed book may appear to have different coloring than what you intended. If you can convert your existing images, or create them from the start in CMYK color mode, you definitely should.
Quality is all about the image resolution (dpi).
Another important setting that each image file contains is the resolution. The resolution tells you how much fine detail the file contains, the greater the number, the higher the quality. For printed images, this quality is determined by the dpi (dots per inch). 300 dpi is the standard for printing and for a print book you should never go below 300 dpi. I would recommend saving all new & future images at 300 dpi so you can be sure your work looks its best.
Scanning images: 300 dpi or higher is better.
When you scan your images into the computer, there are settings you can fiddle with to change the quality of the scan. In the interest of having as much flexibility with your images as possible, I recommend you change the settings so you get a big, high resolution scan to work with. There are some universal settings you can and should change.
TIFF is the best format for images, and the color setting of CMYK is best. I recommend you scan all images in at 300 dpi or higher. You can always go down in quality/size, but not up. For example, if you scan an image at 600 dpi, you have essentially doubled the size and quality of the original image that is on the computer. You could bring that image into Photoshop and have double the detail to work with. The file size is also greatly increased, so be sure to not go overboard with too large a size. 300-600 dpi is probably best.
If you have trouble with your scanner, you may need to do a web search for online help with your specific model and software program. Each scanner uses different software, but third party universal programs for scanning do exist. For Macintosh and PCs, I've had good luck with VueScan.
Let's briefly look at an example image.
I created ClockGuy.tif for my book and the image below shows you what Clock Guy looks like when opened in Photoshop. Next to Clock Guy is a window showing some of the image's settings. To see these settings: open one of your images in Photoshop, then go to the "Image" menu and select "Image Size...".
The checkered grey and white background behind the clock guy means the image is transparent. The checkered part of the image will show whatever color, image, or text is placed below it in Adobe InDesign.
You will notice the resolution is already set to print standard: 300 dpi. The width and height listed are the maximum sizes the image should be printed at. In Adobe InDesign you could re-size the image smaller than this width and height (as long as the image is at least 300 dpi) - but not larger. This is why scanning your images in at a very high dpi is a good idea. You can always go down in quality/size, but not up. If you were to make the image larger than this width and height it would print out looking blurry and you may start to see the square pixels.
The pixel dimensions listed above would really only be important if we were making an eBook or graphic for the web, or re-sizing the image. Since we are preparing a printed book, the width, height, and dpi are the most important settings.
Once your images start to come together, let's move on to talk briefly about the text for your book.