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Forums > Digital Art and Retouching > Can someone explain Minimum dot and where to use ? Search   Reply
Photographer
Hemera Visuals
Posts: 18
Dumfries, Scotland, United Kingdom


Hi there everyone just watch a Gry Garness video where she uses minimum dot so that in the sky in the example she uses doesn't turn to complete white. Is this something that needs to be done to all images going to print that may clip in the highlights ?

Thanks Cam smile
Feb 10 13 10:13 am  Link  Quote 
Photographer
I M N Photography
Posts: 2,297
New York, New York, US


Hemera Visuals  wrote:
Hi there everyone just watch a Gry Garness video where she uses minimum dot so that in the sky in the example she uses doesn't turn to complete white. Is this something that needs to be done to all images going to print that may clip in the highlights ?

Thanks Cam smile

It would help if you add a link to the video, but my "bad" experiences with clipping have been resolved by mapping the images to values lower than 255.

Feb 10 13 10:36 am  Link  Quote 
Photographer
Hemera Visuals
Posts: 18
Dumfries, Scotland, United Kingdom


its an offline video .Ah right i see what you mean :0
Feb 10 13 10:43 am  Link  Quote 
Photographer
Herman van Gestel
Posts: 1,973
Amsterdam, Noord-Holland, Netherlands


for commercial offset-printing minimum dot is usully around 3%....so stay with your whites up to 255-3% == 247

it depends raster, pritning technique (off-set or engraved or flexo), type paper, density of ink..but 3% is a general value...
Feb 27 13 02:55 am  Link  Quote 
Photographer
Daniel Ecoff
Posts: 414
SHERMAN OAKS, California, US


Yes. what Herman said.

Its generally referred to as clipping. You can see clipping in your histogram as well in Photoshop. Just sample your dynamic range and stay away from anything that is clipped... 0-255  .. 3% to 97% effectively.
Feb 27 13 10:33 am  Link  Quote 
Photographer
Leonard Gee Photography
Posts: 16,080
Sacramento, California, US


It applies only to the process of printing on a press and translated to the photographer, it means to expose so there is detail in the sky. Clipping means there is no detail and the highlights are pure white. Good judgement is the main thing.

Minimum dot is the smallest ink dot that the printer can hold on the paper. In general 3% is the industry norm, but that can grey out the highlights in certain situations especially with higher resolution screens. 200-300 dots per inch means there is more ink on the paper than a 150 dot screen. But a good printer with the right conditions can do better than a 3% dot. And if there is no detail in small parts of the sky and the gradation isn't too drastic, I tell them they can let it go.

I would much rather have a image with good looking dynamic range and clean whites than be over conservative and have grey highlights when the image warrants it. But that varies with the image since some low key images look great without any whites.

Better instructions would be, pinpoint dot in the highlights were there is detail and let it go white in the specular highlights or where there is no detail. But it's a judgement call depending on the image, the press, the paper, the run speed and the press operator.
Feb 27 13 10:55 am  Link  Quote 
Photographer
Mask Photo
Posts: 1,382
Fremont, California, US


Leonard Gee Photography wrote:
Better instructions would be, pinpoint dot in the highlights were there is detail and let it go white in the specular highlights or where there is no detail. But it's a judgement call depending on the image, the press, the paper, the run speed and the press operator.

OP was watching Gry Garness's vid on retouching, in which she uses a ~251,251,251 layer, blended to "darken" to bring back the overcast sky so it won't be "paper white".

(one of the primary things i learned watching that video series is that the sky is ALWAYS overcast in britain! "here's a pic i shot..." white sky over and over again!)

251-all in rgb translates to 1% in each of c,m,and y channels, which makes sense for offset printing, which is done in CMYK. It means that there will be *something* in the white areas.

I do NOT agree with Gry that it's best to apply this in a whole layer, because specular highlights *should* be "paper white" (zone X in the zone system). IMO, it should be masked in where needed to preserve any speculars in the image (else why even go to 255 in each channel?)

Minimum dot sounds very similar to what we'd do in the darkroom in basic b/w photo class. If you effed up and got no detail in the sky, fade it in with a moving burn board and a bare bulb so you have at least a boundary for your photo, so it's not bleeding off the edge of the page.

Feb 27 13 09:49 pm  Link  Quote 
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