Vinyl image for wall

[Quinsfan]

Hi guys
I know that this is not strictly Dye sub but I have been asked to quote for producing and installing an image onto vinyl for a wall in an office block. I have installed many of these kinds of things at Gatwick Airport for many years with a previous employer but have never had to to do actual production.
My client have given me a very good quality image with a high resolution. I have scaled it to size 2000x2400 and have printed a section off on A4 photographic paper which I sent to my client as a scaled sample. They have rejected it saying it is to jagged and can I put a gaussian blur on it. This I have done and it looks shocking!!
I have measured the pixels at full size and they measure less than 1mm. As I have never had to produce an image before is there another way of trying to smooth the image? I am unable to post a picture here due to size of it but am willing to send it to someone if needs be.
Many thanks

[NikGrey]

Can you trace it in Illustrator? make it a Vector or is this not possible in your situation?

[daviddeer]

What resolution is the image? Is it tiff or jpeg? What is the original size? What is the file size? What program did you resize it in? What program did you print it from? What printer did you use? What were the printer settings?
Generally you simply load the original image and print that and fit to page in the print dialogue. Resizing an image within a program can be very lossy depending on the program you use and the method of resizing (e.g. bi-cubic)
1mm pixels are very large and will definitely give you a jaggy/grainy print. If is was supplied as a jpeg it will be lossy and will not give you the required resolution when printed wide format.
As a guide I would request it as a tiff at 300dpi minimum or a high resolution pdf at full print size. The choice of wide format printer will also affect the finished output as many cheaper solvent printers and older pigment/dye inkjet printers will not give you the print density you require.
Gaussian blur is a smooth blur resembling that of viewing the image through a translucent screen. It will reduce noise but also reduce the clarity of the image. The jpeg noise will also give a jagged appearance to sharp lines, you could de-noise or remove jpeg artefacts but you still have a rather substandard image to work with. No amount of blurring will remove the pixelisation it will simply mask it and degrade the image.
There are so may factors that are unknown about the image it is hard to advise you on the best course of action.
If you choose to wander down the vector route you will need to place the image, embed it and rasterise it, then perform an image trace as a high quality image. This is best performed by cs6 or higher. Personally I have never see the need for a standard print provided it is of high enough quality.