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Author Topic: Costco Prints WAY too dark in Shadows  (Read 52451 times)

Jonathan Wienke

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Costco Prints WAY too dark in Shadows
« Reply #40 on: February 06, 2007, 02:34:22 am »

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Your assumptions about linear mapping from black to white with relative colorimetric and BPC are incorrect. BPC is described in some detail by Adobe here: http://www.color.org/AdobeBPC.pdf.

I never said anything about "linear", I said "evenly", as in even-looking tonal gradations in the final print. I'm well aware that human perception of luminosity is logarithmic, not linear. And my point (which you seem to have completely missed) was that with a good profile, you don't need to manually futz with an image's black point to get a good print, unless you are trying to trade DR for wider shadow gamut. Leaving the black point at 0 and the white point at 255 will give you all of the DR the printer has to offer, whatever that may be. Given the limited DR of most printers, Costco especially) that is a generally a good thing.
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bjanes

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Costco Prints WAY too dark in Shadows
« Reply #41 on: February 06, 2007, 07:40:15 am »

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I never said anything about "linear", I said "evenly", as in even-looking tonal gradations in the final print. I'm well aware that human perception of luminosity is logarithmic, not linear. And my point (which you seem to have completely missed) was that with a good profile, you don't need to manually futz with an image's black point to get a good print, unless you are trying to trade DR for wider shadow gamut. Leaving the black point at 0 and the white point at 255 will give you all of the DR the printer has to offer, whatever that may be. Given the limited DR of most printers, Costco especially) that is a generally a good thing.
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To put things simply, if you squeeze a 2 pound sausage into a 1 pound casing, something gets compressed. Linear and evenly mean that everything is compressed equally. That produces an unattractive result. Most profiles would compress the shadows more so as to maintain the more important mid tones. If you compress the shadows, you will lose gradation there. Shadow compression was clearly shown in my GamutVision plot. What you need to do is to open up the shadows in cases such as the current one where shadow gradation is important. The profile does not know the artistic impressiion you wish to convey. Without black point compensation the shadows would be clipped, and for the umpteenth time I am not talking about clipping or reseting the black point. The black is output at maximum paper black and the quarter tones should be lightened.

Bill
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Jonathan Wienke

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Costco Prints WAY too dark in Shadows
« Reply #42 on: February 06, 2007, 11:14:31 am »

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To put things simply, if you squeeze a 2 pound sausage into a 1 pound casing, something gets compressed. Linear and evenly mean that everything is compressed equally. That produces an unattractive result. Most profiles would compress the shadows more so as to maintain the more important mid tones.

That's not been my experience when using RelCol+BP compensation, and doesn't match the description in the PDF you cited earlier very well. If you look "Step 3: Attempt To Set DestinationBlackPoint" in the PDF, you'll see that the destination profile is examined to see how even the tone curve is, and if the test is passed, NearlyStraightMidRange is set to true, and the tone curve present in the original image is not materially altered during profile conversion, it is simply scaled between the destination white and black points. This is generally what happens when you have a good quality profile on a reasonably well-linearized printer. It is the case with all of the custom profiles I've made for my Epson 7600, Epson R1800, and Canon S9000 printers with My Eye-One Pro spectrophotometer & Eye-One Match. The tonal relationships are evenly scaled to the printer's available DR, and it is not generally necessary to do tone curve adjustments specific to a particular printer. I've done tests printing the same image on multiple papers and multiple printers, and have not observed significant tonal alterations from one print to another. The only noticeable difference was the deeper blacks in the glossy prints, but shadow and highlight details were similarly distinguishable in all of the prints.

If the profile has a lot of lumps in its TRC, then NearlyStraightMidRange is set to false, and then (and only then) the uneven tonal tweaking you're talking about comes in to play, as illustrated in figures 5 and 6. If you need to custom-adjust the tone curve of your image for a specific output device, that's a pretty good clue that the profile is poor quality, or the printer it was made for is poorly linearized. Which goes back to my original point that doing such tweaks is generally a kludge to compensate for a bad profile. If the profile is good quality and made from a well-linearized printer, the only shadow tweaking necessary is to deal with limited shadow gamut.

The whole point of profiles is to eliminate the need for output-device-specific tweaking as much as possible, so that the print matches the monitor as closely as possible within the physical limitations of the devices. The only output-device-specific tweaking you should ever have to do is dealing with out-of-gamut colors. If you have to readjust the tone response curve of the image as well to get a decent print, then your profile has problems and you're compensating for profile deficiencies, not just trying to fit a large gamut into a small space without losing any more aesthetic appeal than necessary.
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bjanes

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Costco Prints WAY too dark in Shadows
« Reply #43 on: February 06, 2007, 10:09:52 pm »

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That's not been my experience when using RelCol+BP compensation, and doesn't match the description in the PDF you cited earlier very well. If you look "Step 3: Attempt To Set DestinationBlackPoint" in the PDF, you'll see that the destination profile is examined to see how even the tone curve is, and if the test is passed, NearlyStraightMidRange is set to true, and the tone curve present in the original image is not materially altered during profile conversion, it is simply scaled between the destination white and black points.
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The NearlyStraightMidRange boolean set to true does not mean that the tone curve is even or without lumps but that the L* source and destination values in the midrange of the curve (as one iterates through l values from 0 to 100 in steps of 1) are approximately equal. Using Gamutvision, I noted that a L* of 50 in the source mapped to L* of 50 in the destination, satisfying this condition. Step 3 is used only to set the destination black point. After the black point is set, the higher tone values are determined by the black point scaling included in the lookup tables of the profile. This is clarified by examination of the Gamutvision plots with black point compensation off and then on.

With BPC off, the D-Max of 1.79 is reached at log (pixel level/255) of about -0.8 or a pixel level of 40 in gamma 2.2 space. Equal changes in the log pixel value cause equal and proportional changes in output density. Below this level, clipping occurs.
[attachment=1775:attachment]

With BPC turned on, the D-max of 1.78 is reached at input log pixel value of -1.3 or a 2.2 gamma pixel value of 13. A density of 1.8 corresponds to L* of 13.15. The DestinationBlackPoint is therefore L* 13, which coincidently is also the 2.2 gamma pixel value. Input L* of 0 is mapped to output L* of 13.15. On checking in Gamutvision, the lowest L* I found in the OP's image was L*= 0.99 with output L* of 13.90, which correlates well with the graphically derived value. Equal changes in log pixel value of the source image yield smaller changes in output density as the pixel values go towards black. This is not the even spacing you predicted, but rather represents compression of the shadows.
[attachment=1776:attachment]

The same thing is observed in the Gamutvision 3D plot. Source L* of 1 are raised to L* of 13 in the output, and higher values of L* are compressed to a lesser degree, but not proportionally as you claim.
[attachment=1777:attachment]

For those who do not wish to perform the calculations for Log(Pixel level/255) to pixel value, this table does the work and also gives the L* values as calculated by Bruce Lindbloom's companding calculator:
[attachment=1779:attachment]

This table displays output density with the corresponding Percent Reflection, L*, and 2.2 gamma pixel values:
[attachment=1780:attachment]

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This is generally what happens when you have a good quality profile on a reasonably well-linearized printer. It is the case with all of the custom profiles I've made for my Epson 7600, Epson R1800, and Canon S9000 printers with My Eye-One Pro spectrophotometer & Eye-One Match. The tonal relationships are evenly scaled to the printer's available DR...
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False, as shown above. The shadows are compressed.

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If the profile has a lot of lumps in its TRC, then NearlyStraightMidRange is set to false, and then (and only then) the uneven tonal tweaking you're talking about comes in to play, as illustrated in figures 5 and 6. If you need to custom-adjust the tone curve of your image for a specific output device, that's a pretty good clue that the profile is poor quality, or the printer it was made for is poorly linearized. Which goes back to my original point that doing such tweaks is generally a kludge to compensate for a bad profile. If the profile is good quality and made from a well-linearized printer, the only shadow tweaking necessary is to deal with limited shadow gamut.
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False as explained above. Figures 5 and 6 are for determining the destination black point when NearlyStraightMidRange is false. After the destination black point is calculated, the same mapping is used as when the flag is true.

Bill
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Ray

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Costco Prints WAY too dark in Shadows
« Reply #44 on: February 07, 2007, 02:48:51 am »

Just to lighten the conversation a little, I'd like some advice on the various rendering intents. With an Epson 7600, premium lustre paper and the Bill Atkinson profile, I find that both perceptual and rel col require massive adjustments to the image (proof colors and simulate paper color on) to get a print that matches the monitor experience. Absolute col produces a more accurate print without any such adjustments, except with regard to out-of-gamut shadows which are easy to lighten and bring back into gamut. Saturation Intent actually significantly increases the over-all saturation of the image on the monitor, generally without producing any out-of-gamut colors.

As regards which intent to use, I find I'm flying by the seat of my pants; juggling the necessity of adjusting the images in one rendering intent as opposed to not adjusting, or making a lesser adjustment, with regard to another rendering intent.

Is this normal?
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bjanes

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Costco Prints WAY too dark in Shadows
« Reply #45 on: February 07, 2007, 07:46:18 am »

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Just to lighten the conversation a little, I'd like some advice on the various rendering intents. With an Epson 7600, premium lustre paper and the Bill Atkinson profile, I find that both perceptual and rel col require massive adjustments to the image (proof colors and simulate paper color on) to get a print that matches the monitor experience. Absolute col produces a more accurate print without any such adjustments, except with regard to out-of-gamut shadows which are easy to lighten and bring back into gamut. Saturation Intent actually significantly increases the over-all saturation of the image on the monitor, generally without producing any out-of-gamut colors.

As regards which intent to use, I find I'm flying by the seat of my pants; juggling the necessity of adjusting the images in one rendering intent as opposed to not adjusting, or making a lesser adjustment, with regard to another rendering intent.

Is this normal?
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At the risk of oversimplifying things, I have found this link useful in understanding [a href=\"http://www.steves-digicams.com/techcorner/July_2005.html]Rendering Intents[/url].

Perceptual was formerly recommended by many experts if there are a lot of out of gamut colors in the source and relative colorimetric if there are only a few out of gamut colors. The problem with perceptual is that it is not "smart": it looks at the container (color space) of the image rather than the colors that are actually present in the image and may apply more compression than is necessary.

For this reason, many experts prefer relative colorimetric and tweak the out of gamut colors to bring them within range. Bruce Fraser gives some examples. Absolute colorimetric and saturation intents are not normally recommended for photographic printing.

The above is probably nothing new to an experienced photographer as yourself, but it does sound as if there is something wrong with your setup. Is it monitor calibration or are some of the orifices of your printer plugged up? Or do you simply have very difficult to reproduce images with a log of out of gamut colors? If a color in the image is out of gamut for the monitor, it simply can't be reproduced on screen and soft proofing may fail. This situation is less likely if you use aRGB or sRGB as your working space, but often arises with ProPhotoRGB. 3D gamut mapping software such as Gamutvision or Colorthink might be useful in addressing the problem. The better inkjet printers such as yours can print saturated colors at low luminosity that are outside of the gamut of most monitors.

Bill
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Ray

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Costco Prints WAY too dark in Shadows
« Reply #46 on: February 07, 2007, 08:03:02 am »

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The above is probably nothing new to an experienced photographer as yourself, but it does sound as if there is something wrong with your setup. Is it monitor calibration or are some of the orifices of your printer plugged up? Or do you simply have very difficult to reproduce images with a log of out of gamut colors?

Bill,
My prints match what I see on the monitor, including the most subtle shadow details, so I have no reason to suppose there's anything wrong with my setup.

It seems to me there's a significant variation in how rendering intents react with different profiles for different printers and papers. My printer takes 30m rolls which I don't change often. Premium Lustre is the paper I use most and I merely make the observation that Absolute Colorimetric has the least effect on the appearance of an adjusted image with this paper and profile when using custom proof. The perceptual and rel col intent require significant increases in saturation and contrast before printing an image.
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Ray

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Costco Prints WAY too dark in Shadows
« Reply #47 on: February 07, 2007, 08:41:56 am »

I'll specify my equipment, if it makes things clearer. Pentium dual processor 3.00Ghz, Win XP 64 bit edition, Sony G400 19" CRT monitor (quite old now), Eye One Display 2 colorimeter, Matrox Millenium PCIe 128 video card, Epson Stylus 7600 printer, Epson Premium Lustre paper, Bill Atkinson profile.
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bjanes

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Costco Prints WAY too dark in Shadows
« Reply #48 on: February 07, 2007, 08:44:45 am »

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Bill,
My prints match what I see on the monitor, including the most subtle shadow details, so I have no reason to suppose there's anything wrong with my setup.

[a href=\"index.php?act=findpost&pid=99630\"][{POST_SNAPBACK}][/a]

Ray,

Now I am confused. It seems to me if "massive adjustments" are necessary for the soft proof on screen to match the print, something is wrong. The quote above does not seem  consistent with the quote below.

"Just to lighten the conversation a little, I'd like some advice on the various rendering intents. With an Epson 7600, premium lustre paper and the Bill Atkinson profile, I find that both perceptual and rel col require massive adjustments to the image (proof colors and simulate paper color on) to get a print that matches the monitor experience."
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Ray

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Costco Prints WAY too dark in Shadows
« Reply #49 on: February 07, 2007, 09:49:09 am »

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Now I am confused. It seems to me if "massive adjustments" are necessary for the soft proof on screen to match the print, something is wrong. The quote above does not seem  consistent with the quote below.
[a href=\"index.php?act=findpost&pid=99636\"][{POST_SNAPBACK}][/a]

That's how it is, Bill. I tell no lies. My prints, whatever adjustments I have made, match very closely the detail, saturation, tonality and contrast that I see on my monitor.

However, the appearance of the image changes significantly on my monitor when I toggle between the various rendering intents, in relation to the premium lustre profile and with 'paper color' ticked in proof setup.

Specifically, perceptual and rel col dull the image significantly (on the monitor). Absolute col leaves it looking approx the same but with a risk of shadows being out-of-gamut. Saturation intent has the effect of boosting over-all saturation but generally without the effect of inducing out-of-gamut colors.

My work flow is generally to get the image looking right without reference to any specific profile, and then make adjustments later in relation to a specific profile with 'proof colors and 'gamut warning' ticked.

Absolute col intent generally requires the least further adjustment to the image in 'proof color' mode.
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Jonathan Wienke

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Costco Prints WAY too dark in Shadows
« Reply #50 on: February 08, 2007, 03:59:42 pm »

Bill, I think I've figured out the root of our disagreement, and we're both right , to an extent. You are correct that there is a bit of a toe and shoulder built into the luminance curve of profiles. But I am also correct in stating that a good printer profile does not alter the tonal relationship between the highlights, midtones and shadows, when printing using relative colorimetric + blackpoint compensation, from what is observed on the monitor. Here's why: If the monitor and printer profiles are both generated to the same standard, the same luminance TRC will be used in both profiles, and when luminance values are scaled from one profile to the other, they stay in the same places on the curve; the curve is simply stretched or squashed so that the endpoints are attached to the white and black points. As a result, the behavior I have observed when preparing thousands of images to be printed is that the relationship between shadows, midtones, and highlights are NOT altered, the overall contrast will change somewhat, depending on the specific printer and paper type, but that is it, as long as all image colors fall in the printer gamut. A grayscale step wedge that appears to have even tonal gradations on-screen well also have even tonal gradations in all prints. This is especially true in my case, where all my monitors and printers are profiled by the same Gretag-Macbeth Eye-One spectrophotometer and Eye-One Match software.

However, in the case of a somewhat non-standard profile, or a poorly-made profile, the internal TRC's of the source and destination profiles will not match exactly, which means that the TRC of the image is going to be altered, which may brighten or darken shadows, highlights or midtones in relation to one another, or even cause clipping; basically the same effects that can be caused by doing a random curve adjustment on the L channel.
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bjanes

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« Reply #51 on: February 08, 2007, 04:20:17 pm »

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Bill, I think I've figured out the root of our disagreement, and we're both right , to an extent. You are correct that there is a bit of a toe and shoulder built into the luminance curve of profiles. But I am also correct in stating that a good printer profile does not alter the tonal relationship between the highlights, midtones and shadows, when printing using relative colorimetric + blackpoint compensation, from what is observed on the monitor.
[a href=\"index.php?act=findpost&pid=99920\"][{POST_SNAPBACK}][/a]

Jonathan,

Your explanation makes sense, and I am delighted to agree. To be honest, I have never made a profile and rely on the Epson generated ones for my 2200. In this exchange, I have learned quite a bit, and in the process I discovered the profile for Premium Luster Paper that I had downloaded from the Epson site was defective. On examining the predicted DMax in Gamutvision, I discovered that it was 3.82, which is hardly realistic. I communicated with Norman Koren, who supplied me with the correct one, which is on the PSCS2 disc but not updated by Epson on their web site. The correct DMax is about 1.99 and the plot I posted earlier showed much better shadow detail than one can actually get with this paper and printer.

I know the pros use ColorThink, but for me Gamutvision is more ecconomical and Norman's support is superb.

Bill
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Jonathan Wienke

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Costco Prints WAY too dark in Shadows
« Reply #52 on: February 08, 2007, 04:33:47 pm »

Having made all of my own printer and monitor profiles, I knew I had practical experience on my side; it just took me a while to figure out why. No hard feelings.
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dwdallam

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Costco Prints WAY too dark in Shadows
« Reply #53 on: February 13, 2007, 04:08:54 am »

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Having made all of my own printer and monitor profiles, I knew I had practical experience on my side; it just took me a while to figure out why. No hard feelings.
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I'm gonna have some hard feelings if you don't tell me exactly how you want to go about trouble shooting my problem with Costco!!!! LOL

So I had a week off. Not to delve too deeply into my personal life, but  a long lost love--a female photographer working in New York--got in touch with me and said--"It's time we spend time together" I agreed, she took off work, flew out to California for a week, and we disappeared into each other.

In any event, let me appologize again for not getting back to you sooner.

So the original thread is about how to go about finding a solution to images printed at my Costco being way too dark in the shadows and even overall actaully--now that I look at them.

I thought that what I would do it upload the RAW file and a JPG of it after I processed it for printing. Then you would take a look and see what it looks like on your monitor and my adjustments I made in ACR. If it looks close enough to what you would do to get the print to look like your screen, then we know there is a problem with COSTCO.  To confirm that, you would process the RAW file for printing at Costco, I would print your version, and then send it to you in the mail to have a look.

The link to the package is in your PM, and it includes the ICC profile from Dry Creek, the jpg with notes on the conversion, and the RAW file with the XMP sidecar data so you can see my RAW adjustments, and the password for the RAR file.
« Last Edit: February 13, 2007, 04:12:59 am by dwdallam »
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Jonathan Wienke

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Costco Prints WAY too dark in Shadows
« Reply #54 on: February 13, 2007, 12:14:26 pm »

I got you'r PM; I'll work on it this weekend. I have Friday AND Monday off.
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dwdallam

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Costco Prints WAY too dark in Shadows
« Reply #55 on: February 13, 2007, 08:09:13 pm »

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I got you'r PM; I'll work on it this weekend. I have Friday AND Monday off.
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OK great.
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dwdallam

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« Reply #56 on: February 28, 2007, 03:15:44 am »

Jonathan,

I may have fixed the problem. I did two test prints, and they turned out very nice in the shaodws and over all.

I recalibrated my monitor, and when it came to the visual test of "jsut able to make out all of the darker shades, from gray to black blocks) I turned that aspect down on my monitor, which is the brightness. It says tht most of the time you shoould leave this at 100%, but after looking away from teh image and back again, I could still make out all of the shades at 80%. I boooseted it up to 85% jsut to make sure I wasn't kidding myself. Then I went ahead and let it calibrate for color.

I'm still not convinced this did the trick, but I'll write back after I do more tests. As it is right now, they look pretty darn good overall and good in the shadows. If I keep getting this result, then I'll recalibrate and use 80% on the brightness. This should completely take care of any "boosting" of the shadows and overall image brightness that I am still doing--although very little compared to what I was doing.

If you or any of you want to know the results, let me know. I'll post back.
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bjanes

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« Reply #57 on: February 28, 2007, 08:18:58 am »

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Jonathan,

I may have fixed the problem. I did two test prints, and they turned out very nice in the shaodws and over all.

I recalibrated my monitor, and when it came to the visual test of "jsut able to make out all of the darker shades, from gray to black blocks) I turned that aspect down on my monitor, which is the brightness. It says tht most of the time you shoould leave this at 100%, but after looking away from teh image and back again, I could still make out all of the shades at 80%. I boooseted it up to 85% jsut to make sure I wasn't kidding myself. Then I went ahead and let it calibrate for color.

I'm still not convinced this did the trick, but I'll write back after I do more tests. As it is right now, they look pretty darn good overall and good in the shadows. If I keep getting this result, then I'll recalibrate and use 80% on the brightness. This should completely take care of any "boosting" of the shadows and overall image brightness that I am still doing--although very little compared to what I was doing.

If you or any of you want to know the results, let me know. I'll post back.
[a href=\"index.php?act=findpost&pid=103685\"][{POST_SNAPBACK}][/a]

That is interesting, but I don't see how a change in monitor calibration would affect the shadows in the prints, unless you are adjusting the three quarter tones in post processing according to the appearance on the monitor. In other words, a straight print would not be affected by monitor calibration, but print matching with the monitor would be affected

I don't know about your Phillips monitor, but many LCDs are quite bright, ranging up to 200 cd/m^2 and this can cause problems with print matching if you are using standard viewing conditions (D50 illumination at 500 lux). Rather than using a percent of maximum, it would be better to calibrate for output luminance of the monitor, say 120 cd/m^2. I had previously been calibrating to 140 cd/m^2, but some recent threads by experts have suggested that this is too high. What do others on the forum use?

Bill
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Costco Prints WAY too dark in Shadows
« Reply #58 on: February 28, 2007, 08:34:11 am »

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I had previously been calibrating to 140 cd/m^2, but some recent threads by experts have suggested that this is too high. What do others on the forum use?

I have my Eizo CG19 set to 100 cd/m^2 .
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dwdallam

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Costco Prints WAY too dark in Shadows
« Reply #59 on: February 28, 2007, 03:28:44 pm »

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That is interesting, but I don't see how a change in monitor calibration would affect the shadows in the prints, unless you are adjusting the three quarter tones in post processing according to the appearance on the monitor. In other words, a straight print would not be affected by monitor calibration, but print matching with the monitor would be affected

I don't know about your Phillips monitor, but many LCDs are quite bright, ranging up to 200 cd/m^2 and this can cause problems with print matching if you are using standard viewing conditions (D50 illumination at 500 lux). Rather than using a percent of maximum, it would be better to calibrate for output luminance of the monitor, say 120 cd/m^2. I had previously been calibrating to 140 cd/m^2, but some recent threads by experts have suggested that this is too high. What do others on the forum use?

Bill
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That is what I meant. After calibrating and turning down the brightness, I proces images on screen, which are darker on screen than before. Then the images match teh screen better in brightness, especially in shadows.

My Phillips is a 700:1 contrast ratio.

How do I calibrate for output luminance? I have no idea hoiw to do that. However, if lowering the brightness helped shadows and image brightness overall, then if lowering the luminance output would do the same thing, then that is the solution for sure.
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