Paper contrast vs monitor contrast

I've begun printing on my new Canon ipf6300 and the prints look fantastic. I've got the monitor calibrated, and the paper profiles and settings working properly, but one thing I wanted to ask about was the contrast that can be displayed on printer paper versus monitor. The reason I ask is because, although the prints look perfect and match my monitor in just about all regards, the one key exception is dark shadow areas. I've noticed that darker areas which retain detail on the monitor often look pretty dark on the print. This is despite the midpoints of brightness looking equivalent. I've been opening up shadows a little more for print processing because of this.

Are my perceptions valid? Is the monitor more capable than the printer of showing higher contrast with shadow detail at a given level of midpoint brightness?

Thanks for any thoughts.

Brian

Before you print do you proof your image in PS. With my image open in PS I duplicate the image and then with that new image go to 'view'--set up proof--custom then pick the paper profile of the paper I will print on. This then shows how the image will look on the paper. You can then make any adjustments to the duplicated image and use your original image to compare. When you have made them adjustments send the duplicated image to the printer.
Paper choice will also influence how the image looks compared to you original on screen.
Hope this helps I get pretty good comparisons going through this process.

First, many monitors have contrast ratios as high as over 1000:1 where matte papers are around 100:1 and glossy papers about 200:1 so they physically can not replicate the contrast on the monitor. For this reason one must soft proof with the paper profile to insure you are getting the blacks that you want. Often you have to change the black lint setting.

Thanks guys. Yes, I'll have to start soft-proofing. I never really paid much attention to that, but I'll start.

Many monitors out of the box have store display settings of 300 ft/candle white chip backlight illumination. For best dark area contrast tracking, even with calibration, you would want the backlight set to about 125 ft/candles. Then you do your calibration. This provides a dark area response closer to a print as many have found. This has to do with the physics of the LCD panel.

Brightness controls a bias applied to the LCD transparency, not the LCD, so it is possible for some dark area detail to non-linearly punch through the darkest LCD areas of minimum transparency.

My monitor has an 'economode' setting which is defined by percent of backlight illumination. See if yours has this. In addition I assume any consumer fancy content/use auto controls such as dynamic contrast have been disabled. These adjustments affected must remain fixed regardless of content or subject type in order for calibration and viewing to work. If your monitor has any automatic ambient light adjustment it should be disabled and then your monitor should be viewed with minimal light falling on the panel.

That should help with your soft proof response.

Thanks ronzie, I'll investigate this.

There's been a lot of discussion on prints looking too dark on this forum, first step is getting your monitor brightness correct, ideally you want it down in the 90-100 range but very few LCDs can go this low. Then if you want to soft proof you need a calibrated monitor. Next the calibration/profiling assumes a certain illumination level when viewing the print. This is quite a high brightness level, something like 50 cd/m2, can't recall the exact figure, but an iOne 2 will measure ambient light for you. The standard also assumes your ambient lighting is at a certain level, your monitor looks realtively brighter in a darkened room.

I find I do need to open up the shadows a bit, dark toned photos really need to look a bit too bright when I print them to get good tonal separation in the shadows. Ideally you should have a viewing station to judge your prints., but there are some cheaper solutions around now such as this:

http://www.imagescience.com.au/products ... Newsletter

That's why reducing the back light illumination with some kind of economy setting usually helps. The LCD remains in the proper range. Brightness control is usually a bias applied to the LCD transparency. By adjusting backlight illumination the brightness control can keep transparency in the linear range of the LCD.

ChrisRoss wrote:There's been a lot of discussion on prints looking too dark on this forum, first step is getting your monitor brightness correct, ideally you want it down in the 90-100 range but very few LCDs can go this low. Then if you want to soft proof you need a calibrated monitor.
-----------------snip-------------------

That's not my understanding, if you reduce the brightness the backlight source is actually dimmed. Non linearities are introduced as the brightness of the light source changes and is not stable when dimmed too much, a lot of trouble comes about because these monitors are not designed with digital imaging in mind, but are more office/games oriented and are way too bright. The normal recommendtaion is to not go below 10% brightness. This may not be the case for bargain basement monitors but certainly applies to any monitor that is capable of taking a calibration for digital imaging applications. You really need to use the monitor calibrator to set your brightness level to have a stable base from which to judge your images on screen prior to printing.

Most guides will tell you that all you should adjust on an LCD monitor is the backlight, a contrast control if one is suplied will attempt to adjust the ouput from the lookup table and that is not desirable.

Exactly what Chris said!!!

I think that is what is stated. I use an IPS-A panel based NEC P221W. I adjusted the backlight via the economode to 75%, probably can do 50%. There is no other backlight control. Full backlight is 300 Ft.cp. Brightness does not adjust the backlight but the d-c bias on the panel transparency. Contrast is a gain function of the video. It might accomplish this via modifying the LUT table but I would think that would be more a gamma function. Either way I preset it according to the published procedures for calibration.

On dpreview.com's printer forums this has been discussed a few times. I do not have a backlight adjustment on this pro monitor other than the economode. Contrast is set initially per the manual and calibration guide. At that point I let the calibration software adjust whatever it needs too. My delta curves for color and luminance are very good at below 3 deviation for luminance as reported by the calibration application and color deviation is well below the limits. This matches various reviews. Black luminance is .12 ft.cd. I get pretty good print matching allowing for the physics of reflected light (print) versus active light (monitor).

I make no adjustments after calibration of course. The software application and photospectrometer are custom versions of X-Rite's I1D2 system marketed as Spectraview II as branded by NEC.

I get test images from here:
http://www.northlight-images.co.uk/down ... _page.html

and the Print Too Dark article here:
http://www.northlight-images.co.uk/arti ... _dark.html

The backlight control issue I picked up from a few posts on dpreview's printer forum. Anyway I'm getting no discernible color temperature distortion with my setup.

ChrisRoss wrote:
Most guides will tell you that all you should adjust on an LCD monitor is the backlight, a contrast control if one is suplied will attempt to adjust the ouput from the lookup table and that is not desirable.

Ronzie,
I'm trying to figure out why you have to adjust the backlight manually at all. I have the same monitor and also use Spectraview (finally after issues with my Nvidia driver) I tell the software I want 100 cd/m2 and the software does it all, I don't have to touch any of the menu items on my monitor itself. When I look at the menu items after calibration they are set to: Brightness 66%, Contrast 50%, Black Level 50%. These are all set to factory defaults except what Spectraview has changed.

First I'm looking to extend backlight life by reducing its output providing it doesn't take it outside calibration range. The second is possibly getting a better print match by keeping the backlight lower so the static bias applied either to the LCD panel doesn't need to be as non-transparent to get the calibrated black. I'll have to check and see where the brightness was set on my monitor after calibration.

There must be a difference between brightness and backlight illumination because for most monitors brightness controls do not affect backlight life. If you can run at higher brightness (lower backlight and more transparency) and still be within good linear calibration range then why not? In an editor viewing situation you are not dealing with the high ambient light of a store display.

I think of the LCD screen as a variable transparency slide being mounted on a slide viewer panel. If the slide (actually color negative film is a better comparison) is under exposed you might be able to 'punch through' blocked blacks with more illumination or the opposite if over exposed. The idea is to get the dynamic range that best approximates the non-linear characteristics of a print dark area. If your target is web display then this is not as critical. Printer profiles are more about color hue and saturation than luminance. You don't see luminance information too much on a gamut diagram but more about the balancing of the color components.

http://www.color.org/chardata/rgb/srgb.xalter

Now to really get confused look at page 8 here:
http://www.adobe.com/digitalimag/pdfs/AdobeRGB1998.pdf

and settings later on for viewing conditions. They are referring to monitors, not prints from what I can see. I think they mean that the ambient light for viewing a print should be equal to the white point illumination on the monitor. I do not even come close to being any kind of capable expert but just absorb and query findings I come across.

Anyway, I forgot where the idea specifically originated from. It might have been on one of the calibrator or monitor FAQs or support forums.

Too bad I can't get a service schematic. I'm an electronic tech retired from a TV station and familiar with color theory. I have also read in my much younger years subtractive color theory in technical manuals from Kodak. Remember that prints use subtractive technology where color layers filter one another as opposed to monitors where pixel components are adjacent and additive with backlight pass through. I think most LCD panels are stripped. I don't recall the structure of the IPS panel. Now as far as efficiency it is opposite to CRT technology.

http://en.wikipedia.org/wiki/TFT_LCD
look at the different panel type sections

Finally in the NEC manual referring to Economode it states it uses less energy by adjusting brightness. Here I think it refers to 'brightness' in a subjective sense as i don't think the transparency of the TFT panel has much relationship with power draw. It then refers to the Ambibright feature as adjusting the backlight level to compensate for ambient light falling on the monitor. I have that shut off, BTW, and keep my light off the monitor as much as possible so as not to mess with calibration and also to avoid flare.

If I'm incorrect about this I apologize. Bur as others have stated, print matching is best done with about a 100 ft candle white chip leveel no matter how achieved.

I have a headache

I think you'll find the economode is a setting provided to dim the backlight in the absence of calibration if that was required. From what Randy says NEC monitor appears to achieve the 100cD/m2 figure automtically once you give it a target luminance.

If you think about what the panel is doing the brightness setting can only appply to one colour which wold be white, the blacks and anything othet than pure white will have a lower luminance value. So it makes no sense to adjust brightness by applying effectively an ND filter over the panel using the LCD, it would just dramatically reduce dynamic range as the panel has a fixed number of brightness steps and if you use some them up adjusting luminance you would have all sorts of issues with lack of dynamic range.

In any case getting back to the original post the main thing is to target the correct monitor luminance and then do your corrections at the right ambient brightness and view the print under the correct lighting. Now if you are not going to display your prints under the specified luminance you will probably need to make further trial and error adjustments to get the print ,particulaly the shadows, looking right.

Brian-Sounds like your blacks are blocking up and you need to do an output levels adjustment. Print a gray scale chart that goes to about 20 maybe 25 at least. I made my own with 2 inch squares and filled each one with a different level of gray and then collected them all on a couple of pages. You can of course reduce and resize as necessary or desired. Print these and examine after they fully dry where it is that there is no difference between the squares the best that you can discern. If that were to be for example level 14, then put that into a levels layer or curves layer in the output box for the dark's on the left. This will make the picture look funny on the monitor from what it was but pay no attention to that. The printer will then not try to print those lower level blacks that are blocking up. This will then be the output level for that paper-printer combination to use on future images. But beware-- not all images need this adjustment and will be thrown off with it. I still find my self having to adjust certain images by eye with the output amount after I print them. To be honest finding the black limit seems only to be a good starting point many times.

Let us know how you make out.

Paul