peter_wang6

<p>When we talk about an image file as being "8-bit" or "12-bit" or "16-bit," we are referring to the number of binary digits that encodes one channel of a single pixel in the image. Thus, an 8-bit RGB image consists of 8*3 = 24 total bits of information per pixel (assuming no alpha or additional data channels).</p>

<p>An 8-bit binary integer consists of numbers from "00000000" to "11111111". Each place value represents a power of 2, usually starting with the most significant bit. So for example,</p>

<p>10010110 = 1(2^7) + 0(2^6) + 0(2^5) + 1(2^4) + 0(2^3) + 1(2^2) + 1(2^1) + 0(2^0)<br>

= 128 + 32 + 16 + 4 + 2 = 182.</p>

<p>Therefore, the smallest value that can be represented by an 8-bit integer is 0, and the largest is 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 255. An 8-bit image therefore can represents 256 distinct shades of each color channel. With a 3-channel RGB image, this represents 256^3 = 16,777,216 possible colors.</p>

<p>Similarly, a 14-bit image uses a 14-bit integer for each channel for each pixel. This results in a much finer gradation of shades for each color channel, 16384 rather than 256 with 8 bits per channel.</p>

<p>Note that this does not necessarily correspond to a wider dynamic range (i.e., being able to make much finer distinctions between shades of color is not the same as being able to recognize a larger difference between the darkest dark and lightest light you can register).</p>

<p>Sorry, I screwed up the attachments. This photo attachment method is rather clumsy. You can't change the file after it's been uploaded--you can only delete it. :P</p>

<p>Here it is, dark frame subtraction OFF:</p>

<div></div>

<p>But I don't *want* it to look oversaturated, and I can guarantee you that Patrick F. doesn't want that either.... :(</p>

<p>When I open an sRGB image in PS with the color management on, I get oversaturated reds. That's the problem. I don't care about the application(s) telling me my profiles are matching and I've got a color-managed workflow. I don't care that Preview and Photoshop make the colors consistent across applications or in the print output, if the colors they show are consistently WRONG! I care about how it LOOKS and I am telling you that the way Photoshop and Preview are displaying the image is WRONG. At this point, I almost want to throw up my hands in frustration and say I don't care about color management period, because it only makes my images look horrible. I was doing way better without it, things were printing just fine, and I got CLOSE ENOUGH with my results. I don't need it to match up against a spectrophotometer's output, I need it to not look like everyone I take a picture of is afflicted with <strong>rosacea</strong> .</p>

<p>I don't understand how anyone can look at the comparison posted by the OP and tell me with a straight face that the version that Preview is displaying is somehow the "correct" one. His face is WAY too red and it looks like he just tipped back a dozen shots of vodka. I also have a hard time believing that, after all this discussion, nobody has adequately addressed the same question I have asked repeatedly, which is why DPP shows me what I see on my camera's LCD, and what I think the image should look like, no editing, and yet Photoshop doesn't, when both by all indications are ICC-aware apps!</p>

<p>You want proof that I'm using the right settings for DPP? I've attached the preference panes for both DPP and PS.</p>

<p>Look, I'm sorry for the ranting. I know you're all trying to help and I do appreciate it greatly. I'm just so freakin' p***ed off by this issue, which I've never been able to get a satisfactory resolution to ever since I started using color management.</p><div></div>

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<p>Version 3.X and you've invoked color management? Its off by default.</p>

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<p>This could not be true, because I am running Firefox 3.5 on MacOS 10.5.7, and when I checked the settings as you described, it clearly shows that color management is enabled for tagged images (Mode 2, see http://kb.mozillazine.org/Gfx.color_management.enabled ). I didn't do any customization to the default install, so it is enabled by default in the build I downloaded:</p>

<p>Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1) Gecko/20090616 Firefox/3.5</p>

<p>JoeC:</p>

<p>Thank you for posting that image. Here are the results when I viewed it under the following circumstances:</p>

<p>MacBook Pro (personal machine):<br>

Firefox 3.5: Text green, embedded profile is used<br>

Preview: Text green, embedded profile is used<br>

Canon DPP: Text green, embedded profile is used<br>

Photoshop CS2 (North American General Purpose 2): Text green, embedded profile is used<br>

Photoshop CS2 (Color Management off): Text blue/red, embedded profile is <strong>NOT</strong> used</p>

<p>Windows XP (work machine):<br>

Internet Explorer 6: Text blue/red, embedded profile is not used.</p>

<p>Therefore, my question still remains. Here is a sample image that I believe is tagged sRGB. It does not appear the same across the four applications I use on my MacBook Pro. DPP shows the image one way, Firefox, Photoshop, and Preview show it another way. (Apparently Firefox went over to the Dark Side--literally! Not sure how that happened.) How does that happen, if all four apps "passed" the embedded profile test image?</p>

<div></div>

<p>LOL</p>

<p>This is absurd. <strong>The manual for the BODY</strong> contains information on the minimum aperture for which AF is still possible, because it depends on what the BODY's AF is able to do. It's not logically possible to put that information with the lens because how is the lens or the TC supposed to know whether the body (past, present, or future) will be able to focus at f/5.6, f/8, f/11, or whatever? That would be like trying to provide a list of all cars that were ever made, or ever WILL be made, that will fit a given size of tire.</p>

<p>If you want to learn about lenses, just look for the Canon Lens Work book. But don't expect AF aperture to be listed there, either.</p>

<p>Andrew,</p>

<p>Thanks for bearing with me on this. I do know for a fact that the images in question are tagged as sRGB, because (1) they come straight from the camera, (2) I can open up the EXIF metadata and see that the sRGB profile has been assigned, and (3) if I open them up in Photoshop when the working space is not set to sRGB, a warning dialog pops up asking me how to proceed with color management. So by all indications the images are tagged. And since I haven't overwritten the originals, the same data is being read by the various applications, whether it be Preview, Photoshop, Canon DPP, or Firefox.</p>

<p>My confusion stems from the fact that according to Photoshop and DPP, both are ICC-aware applications, yet they read the same data and display it in different ways. The file is the same. The display profile has not changed. Both applications report using the sRGB color space as the working space. And yet, they render the same image in dramatically different ways. And this is what I don't understand, and why I presently believe that a hardware calibration of the display will not help with my issue.</p>

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<p>Unless the browser is color managed (and it would match Photoshop), no, its incorrect. Untagged web doc's are assumed to be in your display profile color space. So to match Photoshop, you'd have to assign this (then they would match although its very unlikely, actually pretty impossible that data from the web is in your display profile color space).</p>

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<p>Okay, so let me see if I understand this correctly. What you are basically saying is that the color managed display (i.e., sRGB captured image, viewed in an application such as Photoshop set to sRGB working space, on a display that is using some calibrated profile), should display colors as they ought to appear.</p>

<p>The logical conclusion to this statement, then, is that Photoshop and Preview are correct but it is the non-managed applications that ignore the ICC tags that are incorrect (e.g., Firefox, DPP). Furthermore, this implies that once the display is hardware calibrated and a custom profile is created, this should in theory make applications such as Preview and Photoshop display correctly, and the non-managed applications such as Firefox incorrect.</p>

<p>Am I correct so far?</p>

<p>The problem, though, is that DPP supposedly supports color management. I have its preferences set correctly to the best of my knowledge. And it displays color in a way that closely matches the output as viewed on the LCD screen of my camera (at least more closely than the oversaturated colors in Photoshop). So if I do hardware recalibration of the display, wouldn't that affect BOTH DPP and Photoshop's rendering? See, this is what I don't understand. And I need to understand this before I splash out $$$ for a color calibrator that I can't be reasonably assured will do anything to help resolve this issue.</p>

<p>But just in case I do eventually get one, which one should I buy? Again, I don't want to spend huge amounts of money. And I need to be able to return it if it doesn't resolve the issue. I'm not exactly ignorant of computer hardware or technology--I consider myself fairly knowledgeable about technical things. But as far as I'm concerned, unmanaged images look to me to be far, far more color accurate than the so-called "managed" renderings.</p>

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<p>At this point, I think the conclusion is undeniable. My sensor is damaged on some level.</p>

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<p>I absolutely concur. This is not acceptable performance out of the box.</p>

<p>The purpose of the test is not to compare the dark frame subtraction vs. no dark frame subtraction images taken on a single camera. <strong>The purpose of the test is to compare the performance across different cameras, both within a particular model and across different models</strong>.</p>

<p>Doing this test is a (mostly) effective way of determining what is considered "normal" noise performance for long exposures within a camera model. For instance, if one user reports much higher noise than others with the same camera, then we should see that in the comparison shots. The only reason to include both noise reduction on/off options is to establish a baseline "off" setting, and then to see the extent to which the camera successfully "hides" these pixels. Because different camera models may do this noise reduction with varying degrees of effectiveness, it is important to see what the unmodified dark frames look like in order to make an apples-to-apples comparison.</p>

<blockquote>

<p>To put it another way:<br /> It used to be the case for me that Safari/Firefox displayed the images correctly, but both Preview <strong>and</strong> Photoshop were over-saturating. I changed the Color Settings in Photoshop to "Monitor RGB - Color LCD Calibrated," and <em>poof</em> , it instantly displayed images with the same color as Safari/Firefox. How can I create a similar "poof" in OSX so it displays that same color?</p>

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<p>I *knew* it. I suspected that you did exactly that, per my earlier post:</p>

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<p>I suspect that the OP's image in Photoshop would look like the Preview/iPhoto display if he turned color management on.</p>

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<p>When you changed your color settings in Phtoshop to Monitor RGB - Color LCD Calibrated, you have basically told Photoshop you want to make your working space your display space, which is apparently not a good thing, because your display space is not capable of showing the wider gamut that the image was recorded in. That's why it matches in PS now, but I don't think that's what you should be doing in the event that you want to print those images opened, edited, and then saved in PS.</p>

<p>I suggest that we all start posting pictures of a 2 min. exposure with and without dark frame subtraction enabled, on cameras that support it. Post 600x600 100% center crops--or better yet, 200% crops because then it'll be easier to see the hot pixels. This way, we can avoid debates over pixel density and sensor area. A hot pixel is a hot pixel. Posting the same image size and magnification will allow us to better estimate hot pixel frequency.</p>

<p>Include the following information: (1) Camera model (2) Dark frame subtraction enabled/disabled (3) exposure time, if not 2 min., and (3) whether you posted 100% or 200% crop.</p>

<p>I'll post mine when I get the chance, which should be sometime Monday evening.</p>

<p>Most young children have not yet undergone the cognitive development that enables them to imagine how other people view them. That is to say, a child is not yet developmentally able to put him/herself in someone else's position. The lack of self-consciousness in front of a recording device is a result of that absence of projective ability that develops in late childhood and early adolescence (and unfortunately, sometimes not at all).</p>

<p>When a child is shy or self-conscious in front of a camera, it is because they have been shown what they look like, thereby forcing that external perspective upon them and causing embarrassment because that perspective does not match their self-image; or that they are reacting to the person recording them.</p>

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<p>Just because it came with the machine doesnt mean its correct... Probability is that its not!</p>

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<p>I understand this, I really do. But at the same time, there's nothing I have been able to do with the display that makes it look any better (and when I mean "better," I mean "more perceptually accurate") than what was set as the default. Yes, it's very likely that it isn't "perfect." But it is close, at least more close than what would be indicated by the oversaturated images in Preview.</p>

<blockquote>

<p>The warning to handle the mismatch has nothing to do with your monitor profile. This is a mismatch between your files embedded colour profile and the default workspace you have set in the Photoshop colour preferences.</p>

</blockquote>

<p>Again, I am aware of this. But the Monitor Color setting in Photoshop CS2 uses the display profile (in this case, Color LCD) as the working space. That I know is not the correct thing to do, but I mentioned it to illustrate what happens when I change the color settings to this option. If I use the North American General Purpose 2 settings, the working space is sRGB and the files are sRGB, and so there is no mismatch generated, but the color is still wrong, whereas if I open the same file in DPP, it is correct. Why?</p>

<blockquote>

<p>How did the image become sRGB? If it wasnt originally sRGB and your merely "assigned" the profile, of course it would be wrong.</p>

</blockquote>

<p>Yes, I know this already too. The images are directly from my camera which has set the profile as sRGB. If I shoot in JPEG+RAW mode, Canon's DPP software renders both nearly identically in color (there may be minor differences due to rendering intent for RAW). But then I open the JPEG in Photoshop or Preview and the colors are oversaturated in exactly the same way as the OP described.</p>

<blockquote>

<p>1) Basically, perform a hardware monitor calibration.<br /> 2) Dont "assign" profiles to an image (unless you really know why youre doing it)<br /> 3) Check what you colour space preferences are set to in PS and as well, how it is set to handle the mismatch - auto convert, ask, etc.</p>

</blockquote>

<p>I don't mean to sound like a broken record, but while your suggestions may be appropriate, they don't address the critical question, which is: Why does the display of the exact same file differ in Canon's DPP software versus Preview/Photoshop? It makes no sense whatsoever. Your recommendation to do a hardware monitor calibration--an expensive proposition--would not resolve this question. To make things even more interesting, Firefox 3.5's default settings also display the same file correctly. I have not assigned profiles manually to any of the affected images--all profiles were assigned by the hardware that captured the image. The preferences in Photoshop should not matter if the working space is the same as the image's profile.</p>

<p>I can understand not wanting to show people the raw photo. It's a bit like a restaurant patron asking to taste the dish after it's cooked but before it's been plated. Straight from the pot, the food tastes the same. But a dish isn't done until it sits there in front of the customer.</p>

<p>But when I do street photos, I will often show people the picture I took. Sometimes I won't, but if I think it's a flattering image I don't hesitate to show them because it helps to make them feel more at ease with the idea that some random stranger just went up to them with a big camera and snapped a few shots. They also tend to ask to be sent the image, which I am happy to do because it's free publicity. When it's a casual event, I also let people see. There are times when I know the shot came out wrong. In such a case, I either delete it immediately, or I keep it in case it's salvageable in PP. If I keep it and the subject asks to see it, I say "too late, I deleted it." Little white lie. But it helps if they see one really horrid photo where one eye is shut, their face is contorted, or the lighting is unflattering. After that, they know better than to ask to see, unless I tell them it's good.</p>

<p>Photographing people has as much to do with social skills as it does photographic skills. You can't hide behind your camera or profess to be some kind of "pro" who just "needs to do his/her job." Every situation is different because you're dealing with different people. You have to know how to gauge their reaction, their comfort level. You do what you can to bring out a person's character and personality, what defines them. The camera is just one component of the dialogue you have with your subject. And the advent of digital photography has allowed us the possibility of using the camera to engage the subject in other ways. You don't have to use the review function. But it is there if the situation, as you judge it, is right.</p>

<p>I have this exact same problem on my MacBook Pro, except that it happens in Photoshop as well. It doesn't happen in DPP. I suspect that the OP's image in Photoshop would look like the Preview/iPhoto display if he turned color management on.</p>

<p>My images are captured in sRGB. If I turn on color management in Photoshop CS2 with North American General Purpose 2 settings, then I get oversaturated reds. My monitor profile is the default "Color LCD" profile that ships with the machine.</p>

<p>If I open an sRGB file using the "Monitor Color" setting, I get a warning asking me how to handle the profile mismatch. If I choose "use embedded profile" or "convert embedded profile" I get the same problem, because this overrides the Monitor Color settings for this file. If I discard the embedded profile, I get the same color as I see in DPP.</p>

<p>When I open an sRGB file in Preview or iPhoto, I get the oversaturated colors no matter what I do. It makes viewing and editing images impossible outside of DPP, which I suppose is okay, since DPP is where I do most of my color-critical adjustments, and I use Photoshop for detailed retouching.</p>

<p>I'm stumped. I've tried calibrating the display using the built-in utility but it is impossible--no matter what I do, the display looks horribly blue. Furthermore, I see no reason to recalibrate the display profile if DPP shows the correct color. I am reluctant to purchase an expensive color calibration product when I don't even know what the problem is. I've read through numerous articles and posts online about color calibration, and none of them have helped.</p>

<p> </p>

<p>Wasn't there some picture floating around here recently, showing some guy walking around with a digital camera in one hand, and a letter-size color inkjet printer strapped to his body like a hot dog vendor at a baseball park?</p>

<p>I think I'd rather be sold a hot dog. :T</p>

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<p>Many professionals post samples on Flickr and other sites as a way of being seen.</p>

</blockquote>

<p>Which, due to the general public's complete ignorance of copyright law, as so aptly demonstrated by the NYT blogger, is why I argue that using Flickr as publicity is a really poor idea. At the very least, if a photographer is going to do such a thing, the samples should never be full size and should always be clearly and indelibly watermarked.</p>

<p>To use the personal property analogy yet again: Not uploading to Flickr at all = not leaving valuables in your car to be stolen. Uploading a small thumbnail = leaving a mockup or facsimile of a valuable (e.g., fake jewelry). Uploading images encapsulated in a Flash program = locking the door. Okay, so it's not a perfect analogy. But the point is that there are many ways to prevent people from casual unauthorized use of your images.</p>

<p>Ah, but I don't think this issue is being taken seriously enough. I actually agree with Les about this--it is a difficult issue and content creators should be more vigilant about protecting their rights. The RIAA/MPAA does a very good job of this because they have enormous financial resources. What of the self-employed, struggling photographer? The law is written to be fair, but its application is all but fair.</p>

<p>Les: I'm not saying that the arguments I presented in my previous post are what I personally believe is right or even legally valid. I am trying to illustrate that in many cases the law has not sided with content creators as a result of some of the arguments I have put forth above. As a result, there is a burden of responsibility upon content creators to ensure that they take appropriate measures to safeguard their work from infringement, and that includes the use of Flickr. I would also argue that such safeguards apply to any site that is not hosted and managed by the content creator for the specific purpose of establishing their online business. Whether such measures are overkill or not is besides the point. In this day and age, the law may still be the law, but you don't leave your car unlocked just because the law says it's illegal to steal.</p>

<p>Furthermore, what is substantively different from viewing a shared image on the web, and printing it? These days, the line is quite blurred. There are such things as digital picture frames that display images directly from the web. Like I said, it may not be "right." But technology moves fast and there are ways in which original works may be used that were not previously anticipated.</p>

<p>I think photographers need to do a better job educating the public as to the issues of ownership regarding photographic works, especially given the current atmosphere of ubiquitous media and instantaneous information dissemination.</p>

<p>To be fair, if a photographer posts a picture on Flickr and makes it publicly available, they can't really have much reasonable expectation that their work won't be appropriated in ways that disregard their copyright. If a photographer really thought it important to safeguard their ownership rights, they would not upload their work onto Flickr for everyone to see, download, and use, Creative Commons licenses be damned.</p>

<p>That's the thing about CC: It's legally valid but just because unauthorized use is restricted by law, does not mean it will do anything to stop infringement. It's a bit like home security to stop theft. Just because trespassing and theft is illegal, does not mean everyone can now just leave their doors open and unlocked at all times.</p>

<p>But let me also point out that copyright infringement is not quite the same as theft. If you steal someone else's personal property, you have taken something from them. They no longer have it. But copyright infringment is unauthorized reproduction or duplication of an original work. If someone makes a copy, they have not taken your original. You still have it. You may be entitled to remuneration or additional damages for the presumed loss of revenue that would have been generated from the sale of that work, but that is an entirely different legal position than outright theft. That is not to say one is more acceptable than the other. It simply means that the precise term to describe the proposal put forth by the NYT blogger is "advocates copyright infringement."</p>

<p>The problem though, as described above, is that the owner of the work, by making it publicly available on Flickr, weakens his/her own claim on copyright, because the simple act of accessing the web page containing the image automatically results in the creation of a local copy on the client's machine. Furthermore, publishing the work under a CC license actually permits such "personal use" as described in the article. That is the argument the blogger is using to justify their actions.</p>

<p>Another issue arises regarding the use of Flickr and CC, which was illustrated in a still-pending case. The photographer cannot sign away the rights of people depicted in the image. So for instance, if I take an image on private property of someone who gives their verbal consent but does not sign a release granting commercial use of their image, I cannot then license that image under CC (except if tagged non-commerical use only). Here's how it works: Say I take personal images of a friend doing something embarrassing or silly while on their property. We have an implied agreement that such an image is okay for our own personal use. But then I decide to share it, publicly, with our mutual friends via Flickr, and tag it CC. This is where I've now done something wrong, because the subject has never consented to the commerical use of their image, and I have now misrepresented that fact. A company finds that image and decides to use it in an ad campaign, causing my friend serious distress and loss of privacy that was unanticipated. Who does my friend sue? The publisher, or the content creator, or CC?</p>

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<p>use them on the business end of a $1500 lens.</p>

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<p>Hmmm....that got me thinking. Which end is the business end, the front or the back? They kinda "do business" on both ends, don't they. I like that phrase. Makes me feel like my lenses are making complex negotiations on my behalf. :D</p>

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<p>How is that lesson for everyone else? If you're upset with the vendor, take it up with them directly rather than dragging them through the mud here.</p>

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<p>It was a lesson for me. I wanted to share it. Is that such a horrible transgression that I'm not permitted to discuss on this forum?</p>

<p>Furthermore, did I actually drag the vendor through the mud? Everything I said was factual. I even mention how one of their biggest competitors, B&H, charges $100 more than Adorama did last time the product was available on the site. And I keep reiterating that I don't even intend to never buy from them again--I just realize that I can't assume that they're going to be my first choice every time. Again, if that's such a hard thing for everyone else to hear, then I would suggest they not read what I have to say.</p>