I have a low-res image would anybody explain to me the technique to make it high-res image? It would be really helpful if you could show me how can I improve the resolution, quality or bring out the elements from the image clearly.
You can change the dimensions and/or resolution under Image > Image Size.
However unless your image is vector-based (and from what you've posted it doesn't look like you're working with vectors) you're not really going to add any detail by using the Image Size feature. Technically the file will get bigger but there won't be any more detail, just added blur, and I don't think that's what you're after.
If you can't get a higher resolution image from the source you might want to consider converting the image to vectors and then enlarge it all you like!
When you start with a large, hi-res image and reduce it in size, you are throwing away information, so it is an automated process. When you start with a small, low-res image and you want to increase its size, you have to add information, so it is not automated. The way you add information is literally by painting it in.
So to accomplish what you want to do, you use the existing small image as a so-called “reference” and you paint a large, hi-res painting of it. Exactly like having someone sit for a portrait and you make a painting of them.
I think there is a confusion of terminology. You can indeed make this a "high resolution" image as defined in terms of pixels per inch on screen and dots per inch in print. It will be a high resolution image that can print about postage stamp size. By inference, however, I think you are actually referring to image size which will be more meaningful to bring out the detail. That is the tricky domain the other members talked about in their responses.
Depending on your needs, and how much bigger you want to go, you can try "Image/Image Size" and change the pixel dimensions to, say twice their size. For the sampling option, choose Bicubic Sharper. Take a look at the result and see if that works for you. If it is "somewhat there" then try the following process to add a little more presence:
- Duplicate the layer (Ctrl-J)
- Change the layer blend mode to Overlay, ignore the look
- Go to Filter/Other/High Pass and apply for this size image doubled in size, 4-6 pixels radius while observing the image. Don't over do it
- If it improved the image to look somewhat like the original size, try increasing the size for another 150% and go through the steps 1-3 again
Remember the old adage about sows ears and silk purses and don't raise your expectations too much. This process may give you a little larger image than the one you have without too much loss of apparent quality.