Image Size and Color Space for Digital Projection

[joelh47]

I have tried to find an all-inclusive answer to this on photo.net, but so far

no luck (just bits and pieces here and there). My camera club (Eastern Maine

Camera Club) will be using digital projection of images in our competitions for

the first time in a few weeks. We are trying standardize on image format, size

and color space for all images in order to avoid issues with some images not

displaying correctly. The only thing we know for sure yet about the projector

we will be using is that the resolution is 1024 X 768. We intend to use the

slide show feature in FastStone Image Viewer to display the images one at a

time, in sequence, during the judging. We intend to have all images submitted

as jpegs. My two remaining questions are as follows:

 

1. Since we are using an image viewer which resizes images to fit the 1024 X

768 screen of a PC during a slide show anyway, do we really need to resize the

images ourselves to 1024 X 768 before projection, as long as they are no

smaller than that?

 

2. Some of our members only use the sRGB color space, while others use Adobe

RGB. Should we have everyone convert their images from Adobe RGB to sRGB for

projection? Or does color space not really matter for digital projection?

 

Thanks,

 

Joel

[patricklavoie]

1_No, if no cropping occur you dont need to. BUT i always prefer to do it myself, because i can add some sharpen to the finale size just to pop up a bit the image.

 

2_Yes. web, projection, and minilab printing are best with a sRGB profil. Believe me, it really matter.

 

It is really easy to just et the image from everybody, and do it all yourself with bridge and a action. That would simplify the process and the consistency of the projection.

[Ed_Ingold]

Use Bridge/Tools/Photoshop/Image Processor to copy the files to JPEG, convert to sRGB (if necessary) and fit to a 768x1024 box (or whatever the projector's resolution). The image is not cropped, but a gap will appear between the long side and the display. In lieu of calibration, sRGB will give the best appearance from a non-color-managed application.

 

You can profile the projector if you have the right tools. X-Rite Photo is such a tool ($1500).

[patricklavoie]

I find it easier and cheaper to calibrate it by eye, i just load a BW image that i like to neutralize the projector, a color one that i like to get the color i want, and a step wedge to make sure the contrast is good, this is the only time i use my eye to calibrate anything; i use a colorimeter for any other calibration i migth need.

[marshall]

Our club's suggestions for projection pretty much fit the above. sRGB. We have often (for competitions) required all images to be resized no larger than 768 on the long side (in order to avoid giving horizontals an unfair advantage in size), but 1024x768 makes the most use of the projector.

 

Personally, I always resize and sharpen a little for projection. The real reasons to resize: avoiding aliasing, which can rob an image of its apparent sharpness and it can create jagged lines out of straight ones; delivery - i.e., if people are emailing images in, why crush the email box of the poor soul who volunteered to organize?

[joelh47]

Thanks everyone for your answers. We will be using sRGB with 1024 X 768 jpegs. Now we just need to educate some of our less technically proficient members on how to convert and resize. I know I could set something up to do this automatically for all the images (I am the "poor soul" who volunteered for this), but part of the reason we are doing a digital projection category is to help all members become more proficient with image editing.

 

Joel