i have been facing this problem many times. When ever i save any high resolution image in PDF format, the pictures in the image gets pixelated and the text or any shape remains unpixelated. But whan i view the same image as .jpeg it looks perfect with all the details. The image is fitting to screen of PDF only at 500%, but when i am putting it to 100%, it is coming as small image(image attached). I have attached some image to explain my situation. Please let me know if there is any format of saving files as PDF to get the best output. Or if someone can suggest the best settings to save in PDF.
This is the PDF output -
This is the JPEG output -
These are the settings i used to save as PDF -
This is Photoshop setting of the image -
This is how the Image looks in PDF at 100% -