Digital imaging has many benefits in terms of the convenience of editing images and storing files. But I've noticed a bit of a problem, both in digital astrophotography and in the field of work I'm in (medical imaging) that relates to the use of computer screens. In some instances an image can look fine on one system, but quite different on another and I think its because, the monitors have different response to various colors. So while you may think that your image looks good, has good color balance etc. it may look bad on another screen. I mainly use a laptop with LCD screen but also have access to an older style CRT monitor. Images do not look the same on each of these. But even when comparing one LCD screen to another, theres a difference. The same applies to printers should you want to print out an image.

What are peoples thoughts on this problem?

That's certainly something you have to take in stride when presenting images electronically. There's nothing we can do about it, as screens will always be different, even those made by the same manufacturer. This could also play to our favor in some cases. What may look good on your screen, may look great on mine.

 

TeleNoob:

In some instances an image can look fine on one system, but quite different on another and I think its because, the monitors have different response to various colors

This is exactly the reason that color management, monitor and printer calibration became a big thing in phototgraphy circles, a few (or several) years ago. Since that point, several manufacturers have introduced both monitor and printer calibration devices (photospectrometers and approximations). One company is:

http://spyder.datacolor.com/index_us.php

Gretag Macbeth, Eye-One, ColorVision, and a couple others also offer similar sensors and calibration software.

If everyone kept their monitors calibrated (every week or so), there would be much less variation from one to another.

Robert

I was just over at the Astroimageprocessing Yahoo user group, were a thread discussed this specific problem.

Though proper calibation of the monitor (printer) is required, if you want a photo displayed on your web browser to look the same to another person viewing that photo in his web browser, both of you need to be using a browser that properly passes color profiles (ICC typically) from the photo. The initiator of the thread contends that none of the current popular browsers, except for Firefox 3, does this. IE uses sRGB, other browsers use their own profile. Firefox 3, allegedly passes the complete color profile embedded in the photo.

If the photo originator used a calibrated monitor when he created the photo coloring (photoshop processing for instance), and if the viewers' monitor is properly calibrated, the colors in the photo displayed by Firefox 3, will appear as the originator had intended.

Robert

I brought that up once before when I noticed a difference in how my images looked going from my laptop to my desk top computer which at that time still had a CRT monitor.  I now have a larger flat panel for my desk top so an image now appears very similar on each computer. 
Both My Laptop and My flat panel monitor for my PC have the built in calibration so you can choose which way you want to calibrate them. That helps a lot, but not completely.
It also depends on the overhead lighting that your using, and the angle of your screen.  It's more of a problem with laptops,  orientation(angle) that you're looking at the screen can make the image appear completely different. I always try to ensure my eyes are on a parallel plane with the center of the screen. 
Then there is the human factor!  how your care for your eyes and what they have been exposed to through out the day or night can make a daily difference in your vision. especially tired eyes. 
And there is also the fact that we don't all have perfect color vision.  Most people have some color blindness, some more than others.  Like some cameras, everybody has a different sensitivity to the various colors.  

There is no guarantee our images will look the same to another person on another computer. It should still be close enough.

 

Have A Nice ________  

If a person does not do these calibrations, or if their monitor is misadjusted, too much bright or contrast, or backlight, whatever, could they make an image that looks good to them, but would be unacceptable, to a person with a properly calibrated image? So it would seem a good idea to check monitor calibration before atempting to edit an image. I suspect most people probably haven't even done it once.

tkerr:

There is no guarantee our images will look the same to another person on another computer.

There are no guarantees on anything (other than dying, at some point). The purpose of monitor calibration, using consistent lighting, and passing embedded photo profiles is to enhance the probability that a photo viewers' experience is more similar to the originators intent. That's as good as it gets, until we all have standardized borg visual implants.

Robert

Thanks for your replies. I'd like to get together some tools to check my monitor calibration before atempting to edit an image. Is there anything like software available to help do this? I know people have used these reference images, the ones with the grey-scales and bands of colour.

I've been doing astrophotography for a while now...and I'm not bad at it.   I've never calibrated a monitor using a spyder system.   You really don't need to either.  Just be sure that your whites are whites and your blacks are blacks when it comes to color balance and temperature.   Use a brightness scale to adjust your monitor brightness (http://www.cosmotography.com/images/calibrate.html). 

Likewise, once you've learned a thing or two about histograms and color balance, you'll learn to trust your software ahead of your own impulses.

But the best thing you can do is learn a little about gamuts and color spaces in Photoshop.  Work on images in the "srgb" color space so that your web JPGs look like what it is you were processing. 

Then, have access to multiple computer monitors and look at your images on many of them. 

jballauer:

never calibrated a monitor using a spyder system.   You really don't need to either.

There are hundreds of professional photographers and graphics professionals (some of which know what their talking about), not to mention the obvious software people that feed on that group, that would just shake their heads, and walk away.

The consensus (for at least a few years) among the best of that group, that are earning their living using digital photography, ie. digital capture, film scans, photoshop, a host of other processing and archiving software, AND that pass their photo products via the web (and FTP sites) to other processors and customers is that complete system calibration is no longer an option, but is necessary for the reasons noted in the previous posts.

The only way to come close to guaranteeing that the viewed photo is as close as possible to the originators intent is for all parties to be using color managed software, embedded ICC profiles, proper profile transmission, and (frequently) calibrated components (monitors, etc calibrated to accepted standards).

The best way to calibrate a monitor is by using a spectrophotometer. Once calibrated (weekly or bi weekly is best), the monitor should be used under consistent lighting (level and temperature). Use software that color manages, like Photoshop, and be sure that it's setup to embed the profile in your photos. Even more important for those that want to make prints of their photos, is the calibration of the printer, ink, and paper. Change any, and you recalibrate. Without this, what you see on the monitor, and what you get out of the printer, may be in different quadrants of the galaxy. With proper monitor/printer calibration, the print will, at least, be close(r).

Robert

Robert:

We are hobbyists.  Not professionals.  If we were professionals, the advice would be different.

Ask this same question to the top astrophotographers in the world.  See how many of them use such calibration\ utilities. 

There are other things that costs money in this hobby that are required to produce better images.  I'm just trying to keep people from spending money they don't need. 

Oh, and BTW, I lied slightly...I have used spyders before, professionally.  Just don't feel they are a priority for the hobbyist.

galactic_photog:

The only way to come close to guaranteeing that the viewed photo is as close as possible to the originators intent is for all parties to be using color managed software, embedded ICC profiles, proper profile transmission, and (frequently) calibrated components (monitors, etc calibrated to accepted standards).

Well, maybe. But how do you know the originator's intent?

As Jason Ware has famously said, "astrophotographers either want to make scientifically accurate images, or pretty pictures ... most of us, like me, make pretty pictures." I do understand your points, Robert, and have spent many years producing and using both still and video images for advertising purposes and in printing systems the sort of color calibration you're talking about is imperative (otherwise the color changes from press run to press run--even during a press run--for example).

It may not be as important in digital astrophotography if the originator's intent is simply a pretty picture.

But let's consider both goals for a minute: what about calibration during capture? How do you calibrate the camera? You don't do it visually using a monitor (since a very high percentage of astrophotography targets won't even show up on a monitor "live" during capture), you do it using the tools in the capture software and the camera driver.

I think that is what Jay is talking about.

Whether you're making a pretty picture or capturing data for research, you're using filters along with the camera control software to study the actual data -- which is monochrome. Later, you apply your own judgement (or some standardized settings, if you're trying to be photometrically and chromatically consistent) during processing to create the colors you're after.

If you use the software and camera control settings as I think Jay was suggesting, your result is possible even without a color monitor in the system at all. Often, seeing the image in color is the last step in the process.

I agree that the way to ensure your image appears the same on another viewer's monitor is to use the calibration software and process. But if your intent is to produce pretty pictures, you generally run into the "how close is close enough?" question and for most "pretty picture" purposes, it seems viewers are quite happy with the typical browsers and monitors which are uncalibrated.

jballauer:

We are hobbyists.  Not professionals.  If we were professionals, the advice would be different.

Ask this same question to the top astrophotographers in the world.  See how many of them use such calibration\ utilities

No doubt.

The same situation exists for the thousands of amateur photographers, most rank novices, some very advanced. A few, to several years ago, when most amateur (and professional) photographers were just beginning to enter the digital workflow, they experienced the same problems that were questioned by the OP. The best solution was to color manage. If amateur astrophotographers took the same approach, that has been proven to work for conventional photographers, a few of the green backgrounds, for example, that are seen on otherwise good images, may go away.

Color management tools are inexpensive compared to the costs of telescopes, mounts, cameras, even photo processing software that many beginning, intermediate, and certainly advanced imagers use. There is no cost excuse for not implementing full color mangaement. There are only missinterpreted colors,...and green backgrounds  (I understand that the actual color of the principal subjects we photograph here are less well agreed upon than the colors of earth scenes taken in conventional photography, none of us have personally viewed these subjects, most haven't seen an accurate, high resolution spectrograph of them, hence the need for color exactness similar to earthly scenes may be questioned).

Robert

chipdatajeffB:

Well, maybe. But how do you know the originator's intent?

The intent of monitor/photo file/file transmission color management is to allow the remote image viewer, using his monitor, to view the same shade of blue (green, or whatever) choosen by the image originator, implemented in his photo, and seen by him on his monitor. If implemented, ideally, this would allow the remote viewer to see the photo just as if that viewer were standing in the same room with the originator, looking over his shoulder. The variations pointed out earlier preclude this from being absolute, but only through color management can the differences be minimized. If the originator implemented a shade of color different than what he truely intended, that's his problem.

chipdatajeffB:

It may not be as important in digital astrophotography if the originator's intent is simply a pretty picture.

Maybe, maybe not. The originator may select a neutral sky color in photoshop (or other color managed image processing software), but the remote viewers sees a green cast sky, because his monitor/web browser accenuates the green component of what was a neutral sky. Had both been using full color management throughout the image creation, web or ftp transmission, and remote viewing, there would have been a reduced chance of this (see above disclaimer).

chipdatajeffB:

But if your intent is to produce pretty pictures, you generally run into the "how close is close enough?" question and for most "pretty picture" purposes, it seems viewers are quite happy with the typical browsers and monitors which are uncalibrated.

Why leave additional uncertainties in the system, when there are perfectly good, cost effective, solutions? Thousands are spent on each component we use in order to get that pretty picture. A few hundred more dollars, and a little time each week, can reduce the missinterpretation to our intent, or more accurately to what we implement in the photo.

If you happen to subscribe to any of the various amateur ( or professional) photo mags, both sides of this discussion were played out over the last several years. It would be best to review their archives for unending pro, con, costs, benefits discussions.

Robert

My intent is to learn what the issues are, and what tools there are available, from people who might already know. As I said I work in medical imaging and this is something that we deal with as well, but its not implemented in all areas. It depends on if that level of accuracy is needed by the user. Some remote viewing stations don't need the extra fine tuning, the factory defaults are good enough. But as someone pointed out, if it is inexpensive to do, why not do it then.

I think certainly if we are going to be the originators of an image, those systems should be checked and calibrated, because that will be the original source of the data file. So far I have learned that my brightness was too low, by the gray scale map and now I have a few bitmaps saved in my folder, which I will check now and then before doing image editing.

Even the background lighting of the room I'm in makes a difference, I understand that and some medical monitors do have an ambient light sensor, they increase the brightness/ or decrease it when the room lighting changes.

I am all for calibrating the monitor and looking for inexpensive tools to help me do it. I've seen some systems that come with these colored paper cards, that I presume are held up to the screen and compared, subjectively to a reference image. That might be good enough for me, as I too am only trying to take pretty pictures! Does anybody here use those?

Thanks for your feedback :)

 

Can of worms, Nope, Perhaps a couple!

I like pretty pictures too.  I'm not here to analyze every celestial object captured in an image. I'm not learning astrophotography for that purpose either.  I just do it because I can, and the fact that I can is amazing.. I do it because It is something I enjoy as a pastime. If I ever lose that enjoyment, and it starts to seem too much like a job, then I will probably quit.

I have used those color cards in the past. With my older CRT monitor, But with my new one I don't need that.   

About that can of worms.

First of all "everyone" must remember we are a group of amateur enthusiasts just here to enjoy ourselves and share whatever, and within our personal limits, possibly gain a little more knowledge. We are not a group of professionals here.  
 I can't speak for everyone else, but I prefer to learn how work with and be more proficient with what I have without going out spending all kinds of money on professional equipment. It would be different if my career choice required it, but it wasn't my choice and it's not necessary here.  

Secondly, It won't matter what the intent of the person posting the image really is.  If he or she wanted their images to look the same on every monitor it is viewed on throughout the World Wide Web, then everyone logging onto the Network viewing the image would have to have their monitors calibrated the same.  Let's get realistic here, That just isn't going to happen.  

For all practical purposes the following is the best advice for the overall majority here on the Internet.

jballauer:

Just be sure that your whites are whites and your blacks are blacks when it comes to color balance and temperature.   Use a brightness scale to adjust your monitor brightness (http://www.cosmotography.com/images/calibrate.html). 

 With that said. What is the best lighting to have.  Fluorescent, Incandescent or what?
 I personally prefer fluorescent and that is what I have at my desk. It is a more natural light where the standard household incandescent bulb gives off a slight yellowish tint.  There are also times I prefer no light. 

 

Have A Nice ____________ 

galactic_photog:

chipdatajeffB:

It may not be as important in digital astrophotography if the originator's intent is simply a pretty picture.

Maybe, maybe not. The originator may select a neutral sky color in photoshop

Note the word "astrophotography" in my quote ...

Why leave additional uncertainties in the system, when there are perfectly good, cost effective, solutions? ... If you happen to subscribe to any of the various amateur ( or professional) photo mags, both sides of this discussion were played out over the last several years. ...

Quite true for digital photography magazines. I haven't seen it discussed to any real extent in astrophotography publications. What would be helpful in that regard would be a discussion about what this means to the astrophotographer. I go back to my "close enough is good enough" argument: if the astrophotographer captures white as white, and black as black, and does not apply any significant gamma correction, then he's done the best his camera is capable of capturing. If he does not then follow that process by altering color in post-processing, then he's produced a "neutral" image, insofar as he can.

Now, if the astrophotographer wants to publish his work via the Web, he must either accept that the vast majority of screens on which his work will appear are "close enough" to display his image in a way that suits him or he must go the extra mile and provide the color-matching data.

My argument is that most of us (I know several astrophotographers, not one of whom uses color-matching techniques, to my knowledge -- they certainly don't talk about it anyway) do not care to go this extra mile. So, if there is an article that shows a measureable difference between what we're capturing using our standard methods and some "standard" we should be expected to meet, then that would be helpful. I'm not aware of such an article, but would certainly read it if someone could supply a link.

A new point: I readily confess to being largely color-blind. I see colors, but I don't see them correctly. Therefore, I rely on my image-capture software and stacking/processing software to help me "correct" the color balance in my images. I am therefore probably a good "test-case" for whether, and why, color-matching software and techniques are helpful.

Here's an example to illustrate my point:

The image on the left is color-wise directly as it came from the camera. I used an FL-D (light magenta) filter to enhance surface detail. This skewed the color balance of the camera, which was set for Outdoor (daylight). The FL-D filter blocks green, primarily. I see this image as brown. I actually displayed it against a pantone color chart and matched it to brown. It is not, however, brown at all. So, strike one for visual color balance and match for me (since I'm color-blind).

To color-balance the image on the right (which by the way is exactly the same image from a capture standpoint), I displayed the RGB color histograms and moved them until I had applied enough correction to zero out the differences in brightness of each color (matched them all to the same brightness), then I applied a gamma adjustment (slight S-curve shape, like an integral sign) that altered the overall balance to offset the characteristics of the camera Bayer filter.

A slight histogram stretch (just a few percent) enhanced contrast just a bit.

Which image is more scientific? The one on the left, since it is altered in a known way which could be repeated exactly by anyone using the same equipment. Which is a "better" image? I maintain it's the one on the right. That image already has been used by a professional astronomer who studies the seasonal changes in the North Polar Hood (the blue area at top and left). I sent him both images, by the way.

In my Flickr! albums, the image on the left has been viewed by 1,507 different people, while the image on the right has been viewed by 2,488 -- for whatever that's worth.

Neither image has had the sort of color-matching you're advocating applied. In my opinion, all that would buy me is that once I'd reprocessed the image using a calibrated system is an image that someone else could view exactly as it would display on my own system.

I suggest that very few people actually have the color-matching technology. I further suggest that if the "average" monitor is so far off the mark that it would significantly detract from my image, then most of us are buying very poor monitors.

What I'm wondering is that if I did the monitor calibration, and then reprocessed my image, how much difference would there be between the histograms and RGB values of the before/after images? If the answer is very large, I'd be surprised (but it's possible I suppose). If the answer is very little, then I don't see how it would matter to me or the majority of folks who view my images. I'm not arguing here that there would be zero difference ... I'm just suggesting the difference would be so small as to not be "valuable" (to me, or the vast majority of viewers).

chipdatajeffB:

Quite true for digital photography magazines. I haven't seen it discussed to any real extent in astrophotography publications

The concept of color management has been so thouroughly covered in the conventional photography community, that essentially all intermediate or advanced aamateur photographers are, at least familar with the concept, what it offers, and even a few methods for accomplishing it. The topic has had very little discussion in the astrophotography community. A few of the participants are aware of it (generally the few that are also conventioanl photographers or those associated professionally with graphics and printing).

chipdatajeffB:

if the astrophotographer captures white as white, and black as black, and does not apply any significant gamma correction, then he's done the best his camera is capable of capturing. If he does not then follow that process by altering color in post-processing, then he's produced a "neutral" image,

This is may be close, for the photo that the originator produces, but is only the beginning if that image is passed to another person for viewing on his monitor, especially if over the web.This comes down to how much benefit, how much cost, and how much do you care about it.

I saw another post on this form, were the poster commented that he was using a very expensive (five figure) camera. Assuming a good concept of system balance, I suspect that the rest of his astrophoto setup (focuser, rotator, OAG, scope, mount, guidecam, dome, controller) cost four or five times this amount. He will undoubtedly spend significant time, in at least a couple expensive processing programs before he moves to final processing, in a color managed program like Photoshop, itself an expensive program. He will spend hours (?) finalizing his photo in Photoshop. At this point, he looses any control over the color, as viewed in his photo, by someone else, in their non-color managed web browser, using their own, uncalibrated monitor. I expect that the difference, for most people viewing this image on the web, using a monitor in whatever state, is small (see my above comment concerning actual vs rendered colors of astronomical subjects).

If the expense of color management was high, I'd agree that it would only be applicable to a very small crowd, in restricted cases, but this is not the situation. The color management cost, and effort, is a tiny component of the high expense that the imager has gone to in exposing and processing his image. There is no good reason to ignore it.

Robert

TeleNoob:

It depends on if that level of accuracy is needed by the user. Some remote viewing stations don't need the extra fine tuning, the factory defaults are good enough. But as someone pointed out, if it is inexpensive to do, why not do it then.

Yes

TeleNoob:

I've seen some systems that come with these colored paper cards, that I presume are held up to the screen and compared, subjectively to a reference image. That might be good enough for me, as I too am only trying to take pretty pictures! Does anybody here use those?

Yes, most newer monitors have built in calibration software, and test strips that allow the user's eye to perform the calibration "sensor" function. That approach is better than nothing, probably gets you 80 or 90% of the way there, if you have "normal" color vision. You will need to keep the lighting consistent, both level and temperature (differing standards on this, but generally around 5000 deg. K if you want to adhere to a norm).

If the cost of a sensor and associated software represents a significant fraction of your total system costs, it is probably a better value to just use the cards. If you're using an expensive system, then that sensor will be pocket change (and the hassle of calibrating once, or twice per month, and maintaining a consistent level and color of lighting should be acceptable).

Robert

galactic_photog:

I saw another post on this form, were the poster commented that he was using a very expensive (five figure) camera. Assuming a good concept of system balance, I suspect that the rest of his astrophoto setup (focuser, rotator, OAG, scope, mount, guidecam, dome, controller) cost four or five times this amount. He will undoubtedly spend significant time, in at least a couple expensive processing programs before he moves to final processing, in a color managed program like Photoshop, itself an expensive program. He will spend hours (?) finalizing his photo in Photoshop. At this point, he looses any control over the color, as viewed in his photo, by someone else, in their non-color managed web browser, using their own, uncalibrated monitor. I expect that the difference, for most people viewing this image on the web, using a monitor in whatever state, is small (see my above comment concerning actual vs rendered colors of astronomical subjects).

Might I point out here, Once again, this is a minority of the members here at "astronomy.com forums". The overall majority "DO NOT"  have equipment that cost them 5 figures. The opposite might hold true at some place else but not here.  Please, let's all consider the majority of astronomy.com members who might be reading these discussion threads.
I think this thread has taken a new direction and has been somewhat hijacked.  Differences in a persons experience and their opinions are expected in these forums. That diverseness of the members and their opinions can most often be very helpful, however, I think there comes a point when enough is enough. We're not here to scare anyone away. 

 

Have A Nice ___________