Hope you are well.
Movie Cinemas utilizing digital projection use either a 2k or new 4k system, with 2048x1080p and 4096x2160p resolution respectively. 35mm film projection on average is considered to be around 1200 lines of horizontal resolution.
Standard DVDs at home are 720x480i. HDTV broadcast is 1920x1080i or 1280x720p, i is for interlaced and p is for progressive scan. Old standard NTSC had 525i. 1080i HDTV interlaces 540 lines of information to achieve the appearance of 1080 lines, 720p HDTV is a true 720 lines of information on the screen at each screen refresh.
An 800x600 1.33 ratio projector will display all the resolution of a standard 4:3 NTSC signal or a 4:3 aspect ratio DVD, however at a 2.35 aspect ratio standard DVD you will only be using 340 pixels of the available 600. This is where you will gain even if using a low end 480p 16:9 projector where you will use 363 of the available 480 with 2.35 aspect ratio movies, and will of course get all 480 when watching 1.78 aspect ratio HDTV or movies in 16:9 format.
I will not compare to the 720p and 1080p projectors, you can extrapolate from the above what the numbers will be for those, both much better than the 800x600 and 480p machines.
Movie theaters even utilize standard 1920x1080p projectors for the pre-show and previews, then switch to the 2k or 4k unit for the main attraction.
So, the simple answer to your question is no, an 800x600 projector will not even come close to a 720p when downsampling a Blu-Ray disk. The 800x600 as stated above will be limited to 800x340, compared to 1280x544 when watching movies, most of which are in 2.35 aspect ratio. There are not any currently available 2.35 aspect ratio native consumer displays to eliminate the loss of projected horizontal resolution. Unless you go with an anamorphic lens set up which is very expensive. Even the 720p option does not compare with the extra resolution you see at the Theater with 35mm projection, 2k, or 4k projection.
Hope this clears some things up.
Originally Posted by toshibafan
Another question, When I watch a movie at the cinema I never think to myself "the movie looks blurry or out of focus on the big screen" and, Im guessing here, the resolution of movies at the cinema is the same as tv resolution so surely a 800x600 projector will give quite a good picture??
The price difference between the 800x600 projector and the 720p is 250euro so I really want to understand if the sharpness difference is that big. When Im playing down scaled blu-ray on a 800x600 PJ surely it will look great and better than a movie would at the cinema?