Adjusting Levels and affect on Brightness

weaponx525 · 11-04-2008, 10:38 AM

Hello all

I hope that this is not the wrong place for asking this question. Recently I took some family vacation pics with my K10 and decided that now was the time to try and do some tweaking with the "Levels" adjustments found in Photoshop.

I adjusted the "Levels" of almost all of my pics to bring the left slider and right slider where the histogram begins and ends. I did not adjust the middles slider. I did however adjust some of the pics for overall brightness and contrast.

When I used a print shop to print out the pics, the same print shop I always use for all of my pics, I found that most of all the pics seemed darker than what I am used to.

Maybe the answer is obvious but the main question is: how does the levels adjustment affect the image brightness that much? I understand that without moving the middle slider you are telling the histogram that there are potentially more "dark areas" but I found it strange that all of the pics appeared slightly darker. Even when comparing the original (dark) to the post processed image (definitlely brighter) the developed image was definitely overall darker.

I am at work right now so I can't upload pics to help explain. I hope to upload some pics later tonite. TIA

emalvick · 11-04-2008, 10:48 AM

Perhaps the easiest possibility is that your monitor is set too bright or not calibrated enough. I should add that the calibration / brightness problems could be on the printer's end as well.

I guess the question is how different are the prints from what you are seeing on the screen? Has your workflow changed from what you did in the past? Are the dark prints only something you've recently noticed? I know, a lot of questions, but it helps others target what the problem might be.

Last, another possibility may be the color profile in the images. In using photoshop, do you know whether your photos are being saved with Adobe RGB or sRGB color profiles. You may have it set with Adobe RGB, but most print shops will only work with sRGB and that can result in a slight difference in output, although I'm not sure how much it affects brightness.

Arpe · 11-04-2008, 04:58 PM

Calibrate your monitor. Try these for free-
LCD monitor test images
Photo Friday: Monitor Calibration Tool
Display Calibration - DisplayCalibration.com - Calibrate your computer display or monitor online for optimal viewing. Brightness, contrast, color depth, resolution and freeware software downloads.

*Wheatfield* · 11-04-2008, 05:25 PM

Originally Posted by weaponx525

Hello all

I hope that this is not the wrong place for asking this question. Recently I took some family vacation pics with my K10 and decided that now was the time to try and do some tweaking with the "Levels" adjustments found in Photoshop.

I adjusted the "Levels" of almost all of my pics to bring the left slider and right slider where the histogram begins and ends. I did not adjust the middles slider. I did however adjust some of the pics for overall brightness and contrast.

When I used a print shop to print out the pics, the same print shop I always use for all of my pics, I found that most of all the pics seemed darker than what I am used to.

Maybe the answer is obvious but the main question is: how does the levels adjustment affect the image brightness that much? I understand that without moving the middle slider you are telling the histogram that there are potentially more "dark areas" but I found it strange that all of the pics appeared slightly darker. Even when comparing the original (dark) to the post processed image (definitlely brighter) the developed image was definitely overall darker.

I am at work right now so I can't upload pics to help explain. I hope to upload some pics later tonite. TIA

A calibrated monitor is a beautiful thing, but often the middle slider needs to be moved too.

The left slider affects what the blackest black is, the left one determines the white point (the whitest white), and the middle one is the gamma, or midtone adjustment.
If you are using Photoshop, adjusting the curves rather than the levels will give you some insight, though not necessarily a visibly better result.
Also, is your lab doing corrections?
It could just be bad printing.
Or it could be some of each....

weaponx525 · 11-04-2008, 08:19 PM

Here are the sample pics to illustrate my problem. The first pic is the original, no pp just straight from the camera. The second is the pp pic after I had adjusted the levels. The developed pic ended up somewhere in the middle of the two pics.

*graphicgr8s* · 11-04-2008, 08:23 PM

Originally Posted by weaponx525

Hello all

I hope that this is not the wrong place for asking this question. Recently I took some family vacation pics with my K10 and decided that now was the time to try and do some tweaking with the "Levels" adjustments found in Photoshop.

I adjusted the "Levels" of almost all of my pics to bring the left slider and right slider where the histogram begins and ends. I did not adjust the middles slider. I did however adjust some of the pics for overall brightness and contrast.

When I used a print shop to print out the pics, the same print shop I always use for all of my pics, I found that most of all the pics seemed darker than what I am used to.

Maybe the answer is obvious but the main question is: how does the levels adjustment affect the image brightness that much? I understand that without moving the middle slider you are telling the histogram that there are potentially more "dark areas" but I found it strange that all of the pics appeared slightly darker. Even when comparing the original (dark) to the post processed image (definitlely brighter) the developed image was definitely overall darker.

I am at work right now so I can't upload pics to help explain. I hope to upload some pics later tonite. TIA

Hope your using an adjustment layer and not doing it on the actual photo layer. What version of PS are you using? CS3 does a better job with brightness/contrast thatn the earlier versions. In fact most NAPP instructors use to make a joke of the B/C sliders in the early versions.

*Wheatfield* · 11-04-2008, 10:07 PM

I went after it in curves and this is what I got. To be honest, the file looks to be at least a stop underexposed.

weaponx525 · 11-05-2008, 07:40 PM

Wheatfield, the pic that you posted is it my pic after you adjusted it with curves? It does seem brighter than my post processed one.

I went back to the print shop today and after discussing with the technicians we decided to reprint the photos. They feel that there will be no change (your adjustments seem to confirm this). They gave me a handout to try and calibrate my monitor so I'll most likely try that next. They also mentioned that they check their machines daily (color profiled I think is what they said) so at this point I am a little worried that it is my doing. I will see what happens by the end of the week.

Thank you for all the responses. I hope I can sort this out soon

*Wheatfield* · 11-05-2008, 07:57 PM

Originally Posted by weaponx525

Wheatfield, the pic that you posted is it my pic after you adjusted it with curves? It does seem brighter than my post processed one.

I went back to the print shop today and after discussing with the technicians we decided to reprint the photos. They feel that there will be no change (your adjustments seem to confirm this). They gave me a handout to try and calibrate my monitor so I'll most likely try that next. They also mentioned that they check their machines daily (color profiled I think is what they said) so at this point I am a little worried that it is my doing. I will see what happens by the end of the week.

Thank you for all the responses. I hope I can sort this out soon

It's definitely your doing, I would think. It really just looks like an underexposed file.
The picture I posted is from your original file.

*graphicgr8s* · 11-05-2008, 10:29 PM

Did you shoot raw or jpeg?

**Damn Brit** · 11-05-2008, 11:06 PM

Ask them if they can give you the colour profile for their printer.

*Wheatfield* · 11-06-2008, 06:34 AM

Originally Posted by Damn Brit

Ask them if they can give you the colour profile for their printer.

That's a fairly common misconception. I had a very long discussion with Noritsu Technical about this.
Colour photographic paper fits very nicely within the sRGB profile, and all you need to do is make sure your file is tagged as sRGB.
If the lab is properly calibrated, their profile should be sRGB, even if it is called something different.
An entire industry has grown up around this for no real good reason.

weaponx525 · 11-06-2008, 01:18 PM

I shot mostly jpg for my files. I may have some raw files but the ones I printed are all from jpgs: I simply didn't have time to go through the RAW processing. PP is still very new to me so even if I had used the RAW processor I wouldn't even know if the pic was underexposed or not. The files just appeared to look brighter to me on my monitor and when I printed them out they seemed to be below expectation. One thing I can say is although I always develop from the same print shop this time around when taking pics I tried to use the highest f-stop possible for max depth of field. I tried to stay in the f16 or f22 area. This may explain why most of my pics are underexposed. The reason I chose these higher f-stops was to try some of Peterson's advice in "Understanding Exposure" and metering for the sky: it was very blue on that day.

I actually used Costco here in Canada for my development and they have been very good so far. They gave me a website to check out (drycreek photo I think) and I think that the colour profile and a method to adjust/calibrate my monitor may be available from their website.

I guess at this point I need to find out how to detect exposure levels using Photoshop and adjust accordingly (tips and advice appreciated

). I also need to learn how to use correct f-stops dependent on the subjects at hand and adjust accordingly.

*graphicgr8s* · 11-06-2008, 02:46 PM

Originally Posted by weaponx525

I shot mostly jpg for my files. I may have some raw files but the ones I printed are all from jpgs: I simply didn't have time to go through the RAW processing. PP is still very new to me so even if I had used the RAW processor I wouldn't even know if the pic was underexposed or not. The files just appeared to look brighter to me on my monitor and when I printed them out they seemed to be below expectation. One thing I can say is although I always develop from the same print shop this time around when taking pics I tried to use the highest f-stop possible for max depth of field. I tried to stay in the f16 or f22 area. This may explain why most of my pics are underexposed. The reason I chose these higher f-stops was to try some of Peterson's advice in "Understanding Exposure" and metering for the sky: it was very blue on that day.

I actually used Costco here in Canada for my development and they have been very good so far. They gave me a website to check out (drycreek photo I think) and I think that the colour profile and a method to adjust/calibrate my monitor may be available from their website.

I guess at this point I need to find out how to detect exposure levels using Photoshop and adjust accordingly (tips and advice appreciated ). I also need to learn how to use correct f-stops dependent on the subjects at hand and adjust accordingly.

On a shot like this you could use adjustment layers. This will allow you to do NON-DESTRUCTIVE work on your photos. Plus it allows you to go back and readjust. Also with adjustment layers you can apply the effects to only parts of an image.
If you really want to learn photoshop join NAPP. It's for pros as well as newbies. And the tutorials are fantastic and are done by very knowledgeable folks. https://www.photoshopuser.com/regist...st&code=friend

weaponx525 · 11-09-2008, 07:28 PM

So I got my second set of prints from Costco and things are SLIGHTER better. I asked them to do colour and auto correction for me and it did improve things a little. However my question now is: how can photoshop identify if your pic is one stop over/under exposed? Do you determine this with the histogram?