So far, I haven't mentioned image file types such as JPEG or PNG, because it hasn't mattered to the fundamentals of texturing. However, there are some tricks that make a huge difference to the quality and size of your SketchUp files, and therefore, the speed at which you can model and render your scenes. We are going to quickly discuss the salient points and then come up with a method that will allow you to benefit from the various options you have.
As you may already know, digital images are made up of pixels. Pixels are dots (picture elements) of color, and each image is made up of a grid of these dots. So, for example, a small computer screen has around 786,000 pixels in a rectangular grid measuring 1024 by 768 pixels. A digital camera might take pictures of 8 megapixels or 3264 x 2448 pixels.
In SketchUp, the maximum size for a texture image is limited to 1024 x 1024 pixels by default. If you select a larger image as texture, it is reduced in size...