why multispectral images have higher spectral resolution but lower spatial resolution?

Answer 1

This is a trade-off: if you had both high spectral resolution and high spatial resolution, the time required to collect this information and the memory required to store this information would quickly exceed modern capacities. You can look very carefully at a small area or very generally at a large area. Also, the amount of data to be processed would require a great amount of time or a tremendous amount of computers.

Answer 2

Put simply you can not upgrade an images pixel resolution. You can however subtract from an images pixel resolution. To obtain the highest resolution possible make sure your digital device is set to maximum size and resolution to begin with, as you can always downgrade.. just you can't go back the other way, I'll explain it with more detail. In order to add pixels they would have to be present to begin with. This is one of the limitations of "raster" or pixel based images. Essentially the image is millions, billions, trillions (massive amount) of dots with individual characteristics, they are very small pixels and when added together they present the whole image, just the pixels are so small that you can't tell by normal sight. TIFF is a lossless image format which stands for Tagged Image File Format. These files can be massive in size and the information is a raster format. JPEG or Journalists Photographic Experts Group file format is a "lossy" format and image size and quality can be "one way" reduced. This is achieved by shifting pixels and replacing smaller sections of intensely populated pixel area with a clever algorithm which makes it less noticeable to the human eye that the image has been reduced in quality, for many other reasons file size and image portability. The same is not true for vector images. Flash is a vector format and works by a number (magnitude) and a direction (x, y axis) as coincidently so do all 3D packages. Essentially point A = X and point B = Y then all that is needed to create a three dimensional space is the Z axis. X, Y, Z are the length, width and depth angles required for three dimensional space. The 4th dimension is of course time and this is where animation begins and along a time line or key frame also where it ends. Vector images can be any size required without requiring pixel information. Hence vectors are used for print and sign making or where absolute precision is required on replication. Raster images although they can be converted into vector format by a process of tracing and recreation of the image in illustration mode with multiple layers. However they look more like illustrated art and not like the original pixel precise source, in fact it is an effect that is quite the "In Thing" in media at the moment. A good example of this is the movie "A Scanner Darkly" which uses vector overlays with original source material underneath... check it out!