L2 PDI Thursday last week

Forums Crewe PS Business L2 PDI Thursday last week

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    Thursday night’s PDI

    Was it only me and Ian that thought the projector was giving blown out highlights and very pale colours and contrast? I had done a print of my Clockmaker prior to the PDI with a fairly strong vignette around the subject; however it did not even show on the projected image. There were some very good landscapes but lacked colour and detail in the sky I am sure the authors would not have submitted them like that.

    I was talking to a member of Nantwich at the weekend and he was saying they had the same problem last year, but got it re calibrated over the summer and is now OK. Could it be ours needs re calibrated? Having said that John’s and Bob’s images looked great.



    Pete Robinson

    I thought some of the images looked to light, but not all of them. My PDIs always seem a to light when projected, but I have calibrated my screen with a spider so they should be OK. This time I forgot to change my colour space from AdobeRGB to SRBG and let the app we use covert it. Perhaps this lightens the images? I don’t know also if it depends on where you view the screen from as to how bright it appears. Probably not.



    I thought my 2 mono images seemed a bit lighter and lacking in contrast than expected, but my colour one (Pretty in Pink) was fine … but then it was a very strongly coloured image in the first place.

    It does seem a bit hit and miss.  I did also notice a few light ones from others.



    MONO also have to be callibrated to sRGB—or so the RPS    recommend.



    Since we had the projector the colour calibration has not been touched – it looked fine.

    The light output is actually set lower by using the “quiet” setting.

    We have adjusted the brightness and contrast several times and I am starting to think that setting the brightness high enough to get the full range of tones in the blacks can’t be achieved without the image looking too bright in the mid-tones. The whites are giving a lot of detail – more than the laptop – which is supposed to have a high grade display.

    The problem is a perennial one with digital projectors – they are very bright by nature and you always wonder what the images you send in the national comps actually look like at their end.

    We are going to have another determined attempt to get this right but please bear in mind this inherent brightness. Just as images you are going to print will look darker than your monitor image, projected images will always look lighter.


    Pete Robinson

    I suppose you’ve got to remember that you are comparing different ways in which the images is produced. The print is on paper, the screen version is back lit and obviously the projected version is projected. I think they all use different technologies to try and show the same image so there’s bound to be differences.


    Ian McNab

    The issue is that monitors, printers and projectors differ significantly in how they render brightness, contrast and colour, but the author is editing only for his/her monitor.

    I suspect that callibrating the projector  with scientific precision will not by itself solve the problem. Yes, a perfectly calibrated projector will display a standard image correctly; but we are each editing our own non-standard images on monitors that simply do not display the images as the projector will. It’s a problem of perception, not technical calibration. So what we really need to know is roughly how much brightness and contrast to add or remove before we submit our beautifully edited images for PDI competitions so that they look closer to what we intended.

    I’ve had advice from professional colour labs about how much offset to apply (+/-) to adjust for the difference in brightness between prints and the iMac’s display (which is notoriously bright even when calibrated, as mine is). You’re mislead by the radiance of the screen, so when your images look good on the screen they are too dark for the printer; you have to get the image looking right on the monitor, and then add brightness before sending to the print lab. The advised amount of offset is a rough correction, of course, but it makes a real difference.

    The situation with the projector is the reverse: images that we get perfect on the monitor will be displayed too brightly when the projector shoves a massively greater amount of light through them. Ideally, we’d all edit our images while viewing them on the projector; but given that that’s impractical,  we need to work out some guidance about a reasonable offset (a percentage?number of f-stops?) to apply to images for PDI display. Trying to guesstimate this yourself between one PDI competition and the next is too hit and miss, and will take each of us too long.

    Of course we can’t give everyone a precise offset for their particular computer set up; but having a generic ball-park figure would help. On competition nights, we can all see that the image on the club laptop is darker and richer than what’s being displayed on the projector screen. So one method might be to have a small group of people get together to  adjust the brightness of an image in Photoshop while projecting it, till the projected version looks closer to how the ‘correct’ laptop version did. Then we’d have an estimate of the offset; and we could test it by applying it to an image before projecting it in order to assess the result. Refining this estimate with a few more images would get us a ball-park figure to try at home. We could do a few images at home,  assess the results on the projector, and reach a rough guide to provide for everyone.

    Does anyone have a better idea for getting a real-world perceptual adjustment we could all  use at home to have a better chance of images projecting as we’d hoped? (As I said, I don’t think this one can be solved by calibration alone.)

    [PS There is, of course, always a chance that the ‘brightening / desaturating’ effect in projected images is not linear, and affects some areas of the tonal range more than others. Consequently, some images will be fine when displayed, and others will look awful. Some experimentation needed here!]

    • This reply was modified 6 years, 1 month ago by  Ian McNab. Reason: Added PS


    PEOPLE with blown highlights when projected might well find helpful to start by checking their monitor with the “Grayscale” we all downloaded a couple of years ago. This needs to be accurate before moving on.

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