Over the last few months I have noticed a few images in the PDI competitions at the club and also in the International that looked a little on the flat side when projected.
I have 2 possible causes for this.
1: The wrong colour profile has been attached, for projection it should always be sRGB, if not the project will automatically convert it, although it does a resonable job of it it does make an image look flat and washed out.
2: The images need to be prepared slightly differently for PDI than for printing. This is also dependant on your monitor being properly calibrated for both colour and brightness. My method is to procces the image as if it is going to be printed out, I then make 2 simple changes. If using Lightroom the exposure is decreased by 20 and the contrast increased by 15. If using Photoshop once all other adjustments are done you need to open an adjustment layer and decrease the brightness by -10 and increase the contrast by +15.
Both these changes are done to get over the fact that projectors are inherently to bright and naturally flat the image.
The main problem with any of this is that many people have their monitors set way to bright, Most monitors straight out of the box run at 180-200 candelas per meter squared, for image editing they should be between 80-120. Personally I run mine at 80 Candelas per meter squared.