Try Avoiding big images or Pictures i.e any natural scene, a group of people, merged people etc which has high color definition/resolution:

Advice: Try to use abstracts (brushes, shapes, illustrations, silhouettes etc…) There are many websites from where you may download brushes, shapes and other types of illustrations. Combining these abstracts produces many new concept and Ideas not only for headers but also as for a complete design. It saves time and effort and money which you gonna pay to image providers. They are used as a vector shapes and they are in less size.

Some of good references I found on internet,

Some of the best examples taken from the net without images:-

Please visit our gallery for more samples.

Use of Image:

Don’t convey information with color alone, as different mind has different perceptions. So try to make a communicative header. The images should be theme based and also include client’s IDEA/Requirement.

Advice: You may put an image and then design something according to the image. For e.g. Try use grey scale image for a black colored website. Also if there is need to use for than one image, the images will be similar. The image size should be less than 15 kb.