I don't particularly want to sidetrack the thread into a new line, but....
I'm not sure about this... never hear of it as print practice!The idea is that when printing you force the printer to use ink
'True' white for a print will be the natural background white of the paper with no ink delivered... as I understand it.
You cannot print a pure white by blending the pigments as far as I am aware.
When printing I often want a 'bright' white rather than a 'cream' say, so I choose the paper accordingly.
I print quite regularly and I use print calibration and prepare my own paper profiles and have never noticed any 'artifacts' attributable to ink not being laid down?You can see it on the print.
Last edited by James G; 13th August 2017 at 11:59 AM.
When no ink is used and you look just over the print you can see those areas. Special when printing large prints that can be disturbing. You see those areas as islands. I've seen it many times on photo expositions.
There're printers that print white too. Google on it. I don't print and I can't tell you how it acts with different procedures.
George
I am talking nonsense.
Apologies to those whom I've misled. I've just been to the software and made a profile for my new 5DMkIV, and re-discovered how it works.
We cannot change the clipping points in the camera. Where I got that notion I do not know.
What we do it to transfer the profile, with the clipping points adjusted, from the computer to the meter. We then use the meter to measure the light. We then trust that is then correct (which it always is) and we ignore the 'blinkies' in the camera.
My apologies for offering such misleading information.
By using the Sekonic to measure the light, the one thing we have to do is learn to trust it. The camera will tell you that you are under/over exposed. When I was in Yosemite last year, I realised that I wouldn't be able to go back and do a re-shoot. I had to get it right. With the camera telling me I was over-exposed, I had to trust in the meter. It nailed every exposure perfectly.
Interesting... I've just taken a close look at a few recent prints. Head on, I see no problem. At a failrly extreme angle I can see 'islands'. However I also see a similar effect where deep black is laid down, so the effect is not necessarily related to no ink.You see those areas as islands
It is not present on matte papers, only on Gloss/Lustre.
My maximum print size that I produce myself is A3+ (483mmx329mm), and I have never printed larger, but I suppose on an A2/A1 print the effect would be more noticeable if viewing at a distinct angle. But since printing a deep plack seems to produce a similar effect, I'm not convinced that laying down more ink would help.
I have also just tried an experiment with my Epson SC P500 which uses pigment based inks. Printing a rectangle with a RGB value of 250,250,250 onto a blue sheet produced a greyish 'shadow', that was still a deep blue rectangle and not a nearly white rectangle with a trace of blue in it. So deliberately avoiding RGB(255,255,255) when I want 'pure' white is going to be counter productive.
I think Laser printers which fuse solid pigment to the paper would be different.
I have very definitely seen this in some of my own work. This is especially noticeable if there are specular highlights in an image or a large blown out light source, like artificial lights at night or the sun in back lit shots. If I look at the print at a slight angle, the reflectance of the areas where there is no ink shows up as a "bald" area really sticks out.
The impact on the blacks is more subtle, but the end effect is a loss of detail in the deepest shadow areas of the print. Something I mentioned earlier I mentioned that I was taught to shoot to preserve the highlights and let the shadow details take care of themselves. When it came to printing, I was taught to print for the shadow details.
The root cause of both issues is the printer's relatively low number of distinct colours and tones. While even a very basic computer screen can output 16.8 million colours (sRGB), a printer is not as talented. It can either deposit a colour or not, and in some of the higher end printers we also see the size of the dot being varied, but even here these are either full size or half size. A decent higher end (more than just cyan, magenta, yellow and black cartridges) exceed the tones of the AdobeRGB colour space and in some instances get towards wide gamut colour spaces like ProPhoto.
The solution is quite simple. When printing, set the output black point to 15 and the output white point to 240 and both problems will be solved. I remember seeing the math somewhere and the theoretical actual numbers where 12.5 and 242.5, but unfortunately I can't find that reference right now. What this does is that it applies some small amount of ink in the white areas (i.e. they will not be pure white, but very, very close to it); so the bald areas are not noticeable. It is more noticeable in papers with a bit of a gloss, but can be spotted on matte papers as well.
In the black areas, values of over 240 (242.5?) will have just black ink and no shadow details will be visible.
Your custom profiles will ensure good colour accuracy, but they do not take these other issues into account.
Last edited by Manfred M; 13th August 2017 at 04:59 PM.
Manfred, Iused to do this, (several years and printers ago), but somehow got out of the habit this last year or so.The solution is quite simple. When printing, set the output black point to 15 and the output white point to 240 and both problems will be solved
As I said, inspecting various prints I do see patches as you describe but I have to hold the print at quite a severe angle (60-70 degrees) With the exception of landscape, large areas of white are not particularly dominant in the images I take.
I usually work just with natural lighting and don't do studio work or work in artificial light much, so this may in part explain why I'm not seeing much of a problem with this.