The Perfect Histogram

"High Key" Exposure of Auke Bay, Alaska

I know.  Its been done.  Beaten to death, in fact.  But remember my “mission” for my tutorials.  I have some friends who have asked me to try to translate this stuff into plain English.  My tutorials will never be a substitue for the in-depth, detailed and knowledgeable work already out there.  And, maybe I will even add a point of view or insights that some writers have missed or even in some instances, mislead about the usefulness of the histogram tool.

Now that I have you reading at least this far, I’ll admit, there is no such thing.  I read many comments and texts extolling the virtues of the histogram tool on the DSLR camera back; as well as the “blinkies” (blinking white highlights indicator).  Often, the commentator warns that if there are “any” blinkies, you must dial exposure back until they disappear, and if there is any part of the histogram which spikes and pushes up against either end of the graph, dial exposure up or down until the histogram stays tamely between the goalposts.

To which I say, not so fast!  The histogram and the blinking highlights indicator are tools.  As such there is no “do-all tool.”  Nor is there a set of hard and fast rules which govern the absolute use of the tools.

So What Does a Histogram Do For Me?

It might surprise some digital photographers that the word histogram is not some new digital photography concept.  A histogram is a frequency distribution chart.  The histogram we use on the back of modern DSLR cameras and in software programs like PhotoShop, is a graphical depiction of the distribution of pixels from black to white, with pure blacks represented at the far left side of the graph and pure whites at the far right.  This might lead one to conclude that the “perfect histogram” would always be represented by a symmetrical shaped, such as the histogram shown here.

But in many cases, they would be wrong.

The histogram measures the relative number of pixels at each level of brightness.  So it stands to reason that a properly exposed image that has lots of bright tones in it (for example a snow scene, a water scene with lots of specular highlights, or a “high key” fashion image) will naturally display more of the histogram shape to the right.  Likewise, a night shot, or shot with a lot of dark tones would shift the bulk of the histogram to the left.  A neutral toned image should come closer to the bell curve.  The Histogram for the photo of Auke Bay looks very different, and it should, as the vast majority of pixels are very light tones:

Histogram of Auke Bay Image above

Until recently, the histogram on the back of most cameras only showed us its measurement of the B&W pixels in an image.  That was/is o.k.  In exposure, what we are trying to measure is the relative brightness in an image (or its luminance).  Newer cameras have overlays of red, green and blue.  For our purposes here, we will ignore them (though you should know that the same principles apply, so that if any of them “spike” at either extreme, the histogram is suggesting that the pixels in that color have been “clipped”).

I use the word “suggest” for a reason.

The histogram and the blinking highlights indicator are imprecise measuring tools.  There are at least two important reasons for that.

First, there area times when the image should have portions that these tools will indicate are overexposed.  For example, there are, at times, images that have specular highlights an/or very bright whites that should be pure white.  In this case, the properly exposed image may actually have some small amount of “clipping” (blinking highlights and a very narrow spike at the right extreme of the graph).

In my earlier tutorial, “Getting Exposure Right” I said that photographer should not be fooled into thinking that the light meter in a camera can “think” for her.  The histogram is similar in that regard.  While it differs in that it can measure the overall image exposure before, during and after the fact, it is the same principle.  The photographer must know the overall characteristics of the image and exposure he seeks.  Only by accomplishing that, can the value of the histogram (and the “blinkies”) be appreciated as the very powerful tool that it is.

The second reason applies to raw images (and I hope you are shooting raw images).  The histogram on current DSLR cameras is created, on-the-fly, by the same in-camera software that renders a jpeg image (if you shoot jpeg).  As I opined in “Why You Should Shoot Raw” it doesn’t make sense to go to the expense of a multi-thousand dollar camera, an expensive computer and sophisticated rendering software such as Photoshop, and then let rather unsophisticated in-camera software render your images (“cook” them) in such a way that you have very little ability to “develop” them yourself.  But that is just what the in-camera jpg algorithm does.

It is the in-camera created jpg that the histogram (and the blinking highlights indicator) is measuring; not the raw image.

And, notably, this jpeg-based histogram is not the same histogram you get in Photoshop, ACR, Lightroom, or any other post processing software’s adjustments menu!  So it is very important to understand that your particular histogram my not completely accurately measure what your sensor is able to capture in a raw image.  Like the exposure meter, it is worth doing some testing in a controlled lighting and image environment, taking note of it and making the appropriate adjustment or interpretation in the field.

Your Mileage May Vary.

I have found that on some cameras (true of my D200 –seemingly less so of my D700, which is perhaps a function of the camera companies just getting better and better at interpreting, measuring and presenting what the end result will be), I can push the image beyond the blinkies and spike and still get a very acceptable “default” histogram when I open it in ACR. As we like to say on forums, YMMV.

So What Am I supposed To Do With The Histogram?

Within these limitations it is important to understand the guidelines.  The left and right extremes represent the limits between which the histogram should normally reside.  If spikes upward at either end (left or right sides), the histogram is suggesting that the respective black or white points are being clipped.  Another way of saying this is that the spike and beyond represents areas in the photo in which all detail has been lost in the dark areas, and/or all detail has been lost in the whites (“blocked up shadows” or “blown highlights”).  Importantly, these are guidelines; not rules to be slavishly adhered to.

Histogram of "Underexposed" Image

Histogram of "Overexposed" Image

Now that we know the limitations of the tool and how it works, we can use the histogram to make arguably better judgments about exposure.  But remember, they are just that; judgments.  Once you understand how the tool works and what the information it gives us means, it just makes sense that the histogram for a shot with mostly darker tones would show substantially more information to the left of the histogram:

Split Rock Histogram

Split Rock Lighthouse

 

 

 

 

 

Prior to the advent of this tool most of us only had the light meter and our knowledge of it and of exposure techniques as tools to be used prior to making the exposure.  While in most cases, accomplished photographers knew how to meter and judge correctly and rarely worried about the end result.  In cases where tricky lighting or other conditions prevailed, photographers often either bracketed a series of images to cover any overlap from measurement to reality, or in some cases, took Polaroid shots that could be “instantly” developed and analyzed.  And in the end, you still didn’t really know until you got the developed images back from the processor.

In my view, the time and effort required to get to that point was clearly greater than it is with the modern DSLR and the histogram.  Today (especially when capturing raw images), we can let the camera’s automatic metering make the exposure and check the histogram, adjust and then take another exposure.  And newer cameras with so-called “live view” lcd panels can actually display a “real-time” histogram, which can be used as an additional measuring tool.

I am not suggesting that the histogram be a substitute for knowing how to properly expose, and pre-thinking your shots.

You still need to understand the principles of good exposure before you can use any tool to make well-exposed images, in my view.  And, my “shoot first and ask questions (well, check the histogram) later” approach will not work if you are shooting action or in rapidly changing light conditions (although in an action scenario, such as sports, or in a situation where you are anticipating future action, you can take a test exposure and get the adjusting done before the action starts in many cases).  But for my routine landscape imagery, it is a method that works just fine.  Except in rare or unusual cases, I rarely use the spot metering function on my camera, and never have used (in my recent memory) the weighted average function.  I set it to the “matrix” (honeycomb pattern) meter, take the exposure, and check the histogram.  For good measure I also check the blinking highlights indicator, just to get more information.  In certain lighting situations, I know my particular camera may meter at a certain exposure solution, but I need to adjust the exposure compensation by 1/3 or 2/3 stop.

Raw Shooters: Expose To The Right

One last point; relevant if you shoot raw images, but not so much if you shoot jpeg.  See my previous tutorial, “Expose Right To Expose Correctly,” for an explanation about why it is important to favor, or bias the right side of the histogram in exposing raw images.  In short, the vast majority of information is captured in the highest EV of capture (twice the amount of the entire rest of the perhaps 5 EV range).  Thus, the sensor can capture more important information in the highlights.  It is important not to leave any gaps on the right side of the histogram, and if the photographer must choose or make judgments, the right side should be favored.

For a really in-depth, illustrated tutorial on Histograms, see The Luminous Landscape here.

Epson Stylus Photo R1900 Review

For some time now, I have been considering an “upgrade” to my Epson Photo Sylus 1280 printer.  In December, I purchased a refurbished Epson R1900 Inkjet Printer.

Why did I buy this Product?

Since my fascination with photography began in the early 1970′s, I have coveted a color darkroom.   I was a typical college student with more debt than I should have had, and the cost of purchasing color darkroom equipment was out of the question.  I had all I could do to pay for film and development.  When I graduated from Law School in 1986, I soon found myself with a house payment, children, and payoff of college debt.  By the time I was finally able to purchase darkroom equipment, traditional chemical darkrooms had become essentially obsolete.  The Digital age had dawned.  And suddenly, I already had the color “darkroom” I had always wanted — and maybe more!  A computer and some software gave me access, for the first time ever, to my own ability to “work”  and make my own color prints.

My taste leans (always has) to a traditional photographic paper look and to color.  When photo-quality inkjet printers first came out, they were usually either dye-based, or dye-sublimation type printers.  Their biggest weakness was their lack of longevity.  I still have a print I made on an early Epson Photo Stylus Printer that faded.  When I removed the print from behind the mat, I was astounded at the amount of fading.

Before long, pigment based inks were being touted as having much better print life.  But they just didn’t have the traditional photographic look many of us wanted.  Indeed, the early ones didn’t print well on glossy substrates at all.  While over time, this improved, at the time I purchased the 1280, there were still some issues.  The R1800 had come out, but was reputed to have some issues on glossy prints, including “bronzing.”  I opted for a used 1280 because I wanted to print on glossy photo paper.  The 1280 is a dye based printer and prints very well on glossy papers, but still has the fade/longevity problem.  Over time, Epson (as have the other manufacturers) developed better papers.  I took to printing on their Lustre Paper, which has greater print longevity when matched with the 1280 Epson inks.

The 1280 was not without its warts.  There are no individual ink carts for the color inks.  Just a color cart and a black and white cart.  The color matching capability, even with a calibrated system, is dicey.  I found that a fair amount of trial and error was necessary to get good color results.  Epson does not offer paper specific profiles for the newer papers.  I tried a custom profile and did not feel that the result was better than taking my chances with Epson’s “canned” profile for the Epson Premium Glossy paper (which was recommended even for the Lustre papers).

I had some photographs made to hang in a gallery back in 2007.  The only way the owner would hang them for sale was for me to have them printed with “archival” ink (his definition was pigment based ink like the R1800).  These experiences convinced me it was time to look seriously at a change.

Cost and Availability

Epson advertises the R1900, new, for $550.  From time to time, they offer rebates which can reduce the price to as low as $400.  My refurbished unit was around $350.  These printers are available at Epson authorized retailers and authorized on-line retailers.  They can also be found on eBay (but I wasn’t able to find any selling for less than the refurbished price).  Because of a known issue with ink cart recognition (more later), I opted to purchase directly from Epson. For those who still prefer dye-based ink printer systems, the R1400 is the upgrade of the 1280, and uses longer print-life Claria, dye-based ink.  The R1400 sells for around $200.  The least expensive “photo quality” printer Epson sells is limited to 8 1/2 inch wide paper and sells for just under $100.

The 1280 (discontinued), R1400, R1800 (discontinued), R1900 and R2880 are all capable of 13 inch wide papers and print up to 13 x 19 inches.  Some of them accept roll papers for longer than 19 inches.  the R1900 is roll paper capable.  Epson also has its “Professional Imaging” series of (currently) 8 different printers which range from just over $1,000 to as much as $30,000.

Setup, Operation, and Technical Stuff

In the case of the Epson R1900, I was disappointed find very little conclusive useful information available to enable me to make a final decision.  Consumer Reports didn’t review it.  I did find a comprehensive technical review on Photo-i.  The review gives a detailed idea of how the Printer will render colors, and how it works.  For technical specifications and information, I highly recommend you read Vincent’s review.

Amazon, and some other retail seller sites revealed consumer review comments.  As I have suggested on the Gear Reviews page, these sites illustrate that there is a “love it” or “hate it” tenor to those reviews.  So, my question still unanswered, ultimately, I did what any self-respecting, red-blooded American guy would do.  I took a flyer and bought it!

Do an internet search for information on the R1900, you will learn that the printer has a significant problem!  It is temperamental about how it reads and accepts Epson’s individually-chipped ink carts. Each cart has a computer chip embedded which the printer reads for its on-screen ink level monitor.  Reviews suggested that consumers were having problems getting some of these printers to to work at all.  Many consumers have simply given up on this model and replaced it with something different.  My subsequent conversations with Espon service revealed that they were aware of the problem and it was with the ink cart chips and not the printer.  However, there seems to be experiential evidence that it may be some of both.

My problem was that I have become “married” to the Epson System.  Inkjet Printer inks are generally matched to papers produced by the manufacturer.  There have been great strides made in the past years by third party manufacturers of paper and of inks to make them compatible.  But I have found very good results using Epson’s Premium Luster and Premium Glossy Papers, and to change to another manufacturer meant searching, experimenting with and finding new paper(s).  I wasn’t sure I was up to the task (plus, I had a number of sheets of rather expensive, 13 x 19 inch Epson paper).

For those patient enough to bear with Epson, I believe the reward is worth it.  I purchased a refurbished unit directly from Epson.  To my disappointment, my first unit did just as advertised by the negative consumer reviews.  It simply refused to recognize one of the ink carts (orange in my case).  I ran through all of Epson’s trouble-shooting suggestions to no avail.  I ultimately, called them.  They sent me a couple new orange ink carts.  I tried them both, to no success.  Eventually, Epson shipped me another unit.  This one fired up and I was in business!

A couple of points about how Epson handles this are worth mentioning.  First, it is my understanding that if the unit you receive doesn’t work, they will only ship you a refurbished unit to replace it.  While I think this as an unwise and short-sighted business practice, my workaround was to purchase a refurb in the first place (I have had good success with refurbished and gently used products in the past and there was a small savings in doing so).  They shipped the replacement unit along with a Federal Express ground shipping label.  If you ship from a place of business, they will pick up.  That part went without a hitch.  I received the replacement unit and had it operational before I had to ship the old unit back.  Other than my time, it didn’t cost me anything to do this exchange.  They do, however, put a “hold” on your charge card for the cost of the printer until they receive the old one back.  They also instruct you to remove all the ink carts from the defective unit and keep them (a small repayment for your inconvenience). They indicate (contrary to their literature) that they can be re-used for a period of time.

Is it worth all this hassle?  Maybe.  I had the time and patience to work with Epson and wait for the new unit to arrive.  It made a difference of about a week and I was able to easily do that.  Epson was courteous and prompt in taking steps to satisfy me.

But What about the Prints?

The result, once you get the printer running, is in my view well worth the journey.  I re-calibrated my monitor to have a “fresh start.”  I pulled out a sheet of Epson Premium Glossy paper and made my first print, using the “printer manages color” settings with the Epson “canned” profile for Premium Glossy paper.  I was very pleasantly surprised.  The print came out with very nice color and the glossy finish was superior even to my 1280 prints on glossy paper.  One of the innovations to the R1900 is its extra cart which contains a “gloss optimizer.”  While this appears to have the advertised effect, be forewarned that it gets used a nearly twice the rate as the other inks (at least according to the ink monitor).

The R1900 also has an couple of additional new colors (orange and a second blue, as well as separate black inks for glossy and mat finishes), with 7 ink carts in all.  I am hoping that the separate color carts will make the printer less expensive to operate overall.  The R1900 uses Epson’s Ultrachrome, pigment based inks, which are dry to the touch by the time the print is finished printing!  And because of the newer print head technology, smaller pigment particle size and overall technology in the printer, there is no visible sign of bronzing and metamerism is not noticeable.  I have now made a number of prints of different nature subjects and have yet to have one of them vary unacceptably in color from what I expect based on what I see on the monitor (of course, experienced printers know, you simply cannot exactly duplicate the color and look illustrate on an electronic monitor with ink on paper).  I had so much fun printing that I ran out of paper and am awaiting a shipment.  I made one monotone print and though I am satisfied with it, I do primarily color work.  I understand that the considerably more expensive, R2800, with even more ink color variations, makes superior Black and White Images.

Admitting I was still printing with the 1280 probably dates me.  But one other major pleasant surprise was the speed of printing.  I would usually start the 1280 printing and then walk away, to come back 15 – 20 minutes later.  The R1900 takes just a few minutes to make a 13 x 19 print.  I have read that for those who already own the R1800, the benefit may not be enough.  We can be sure that the major inkjet photo printer manufacturers will continue to innovate and there will likely be a successor to the R1800 – 1900 “family” that will do even more.

I am a hobbyist photographer/printer who does not make hundreds of prints for sale or other distribution.  I make the occasional sale and also prints for my own enjoyment and this printer is a very good choice and fit for these uses.  I recommend this unit for the advanced hobbyist photographer/printer.  If you need to make a significant number of retail prints for sale or distribution, you may want to consider one of Epson’s Professional Imagining” series (R3800 – GS6000), which range in size from 17 to 64 inches wide and in price from $1,200 to $30,000.

Get Real

Last month I had the good fortune to attend one of John Shaw’s 2-day seminars on digital photography and technique. It was a very thought-provoking 2 days for me. As an aside, for a static type experience, I would highly recommend it on the “bang for the buck” scale. John was very open to questions during the seminar (an in some cases, very patient with some of the questions/questioners).

One exchange resonated with me. When asked his opinion about a certain film’s closeness to “realistic color,” his instant retort was: “I could care less!”

With all the debates (on line and off) about realism and manipulation in the digital age, this one hit home for me. Some years back, an instructor in a photo class made the comment that serious photographers do not “take” photographs–we “make” them. I couldn’t agree more with both of these teachers.

I understand there is a place for “reality” in photojournalism and perhaps in scientific photography. But I also appreciate how perception and the limitations of the equipment and media make any absolute “reality” difficult if not impossible.

My own vision is to create what looks good to me from the scene or subject before me. I am not suggesting that we take a blank page in Photoshop and make things up. But colors, composition, cropping and perspective, and yes, even the judicious “photoshopping” (the verb) of an image is perfectly acceptable in my opinion in “making” the image I want the viewer to “see.”

I don’t see this as inconsistent with integrity. Most of my work leans toward “art” and I am not representing otherwise. Are my photos “manipulated?” Yes. Does that bother me? Not in the least.