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DAFOS Photo World

Why??

To catalogue my thoughts and experiences on things photographic and related topics, aiming to promote open-minded creativity and respect that hopefully contribute in some way to general peace and well-living.

Colour management from front to back.

Things Digital Posted on Thu, July 22, 2021 23:54:24

Well, the front part today at least. Regarding the “digital” parts of photography, many articles have already covered the importance of checking that your computer output device (monitor, and eventually printer) are properly calibrated/profiled etc…, so that the colours represented “in the digital domain” (i.e. as numbers in your computer) come out looking like we’d expect them to. Up to now, not so much attention has been paid to what happens before we get into the “digital domain” in the first place – i.e. how the camera we use perceives colours, and also how the lighting we have may be affecting the way it “sees” the colours.

There are basically two things that can affect the way a camera will record the colours in a scene:

  • The light illuminating the scene. For most sources, its “colour temperature” – though other sources like LEDs and low-energy lights have special characteristics too. (These can be weird: they emit light with very irregular spectra, with some colours missing altogether so they could appear as black in your picture!) In general, your camera flash is the best bet where practical, but if you must use continuous lighting, lamps (including LEDs) have a “Colour Rendering Index” (CRI) which must be above 90, preferably 95, if you need to render colours correctly.
  • The camera sensor. Here, problems could be caused by a variety things, but the combined effect of these is that the cameras sensor is a good, but not perfect, converter of light to digits.

Both sources of colour variation can be addressed in one go, by using a colour calibration chart. By photographing this chart alongside the subject of your picture, a “profile” can be built that can be used to cancel out pretty well all of the affects mentioned above.

Looking into what is available, it became apparent that, while support for Adobe products seemed fairly prevalent, other platforms such a Capture One (my photo processor of choice) seemed less well served. X-Rite Pantone® seemed to be the only reputable source of the necessary tools (my ColorMunki Photo monitor calibrator comes from there too). On the basis of this I purchased an X-Rite “ColorChecker passport”, and downloaded its accompanying software.

The colour temperature of the light can, to a great extent, be compensated by selecting the appropriate “white balance” setting, either when you capture the image or in post processing. (If using JPEG, you really must do this when shooting). The camera’s default “profile” can also be used of course, but is this precise enough?

To be honest, for the vast majority of pictures, the answer is yes. But for the specific application I have (reproducing paintings etc…), it may not be ideal. Thankfully, companies the likes of X-Rite, Adobe and Phase One make it very easy to set up the necessary “camera profile” that provides compensation for all these non-ideal phenomena (at least when using raw format), by including the colourful patches in a test shot or two, using RAW format. Process the test shots, assuring that the default profile is turned off (in Capture One Pro, this is under “Base Characteristics” – see the screen grabs: they are similar in Lightroom) and setting the response curve to “linear”, we then need to isolate the colour checker by cropping to it, to make an image suitable for the X-Rite software to analyse.

  Select these for camera calibration

Having done that, we then need to export an image that the X-Rite programme can read. This must be 16-bit TIFF, and not be influenced by any output profile. (For Adobe users, a DNG file can be used instead of TIFF). So, we select “embed camera profile”, which through the above step is now set to be fully neutral.

  Output process

We can then simply “drag and drop” the resulting TIFF image into the X-Rite programme, tweak the automatically detected reference points and let it do its magic. Give the resulting profile a name to remember, selecting “ICC” for Capture One Pro or “DNG” for Adobe, and save it.

Back in Capture One (or Lr / Ps), select the camera ICC profile just created (and select “auto” Curve) in the “Base Characteristics”

and you’re ready to roll with a very nicely calibrated front end!



Turn turn turn…

Things Digital Posted on Sun, August 23, 2020 15:50:02

Not about photography this time, but another web programming exercise. I wanted to make a “spinner” to keep people busy while the new photo carrousel I put in the into section of my website was loading.

As my site is already quite “clunky (*)” I thought to try something using only the built-in features of HTML and CSS (no javascript for this one).

It’s quite hypnotic, and I’m rather proud of it, actually!

(* I’m not a professional web programmer and learned my computer programming skills during my career as a product marketing engineer for microprocessors, and while building this site over the last 8 years or so. Some of the original code I wrote early on is not so easy to maintain, therefore. When I changed jobs a long time ago, I promised myself to not go and learn another programming language – I broke my promise… 🙂 )

<!DOCTYPE html>
<html>
<title></title>
<head>

<style>
.container {
border: black solid 1px;
padding: 20px;
background-color: grey;
height: 500px;
}

.spincontainer {
padding: 10px;
text-align: center;
background-color: lightgrey;
}

.spinpaper {
display: inline-block;
position: relative;
box-sizing: border-box;
text-align: center;
width: 250px; height: 250px;
background-color: rgba(255,255,255,1);
border-radius: 100%;
}

.spintext::after {
width: 100%;
position: absolute;
top: 50%; left: 0;
margin-top: -11%;
text-align: center;
font-size: 2.2rem;
content: "\00231B";
}

.turning1, .turning2, .turning3
{
display: inline-block;
position: absolute;
box-sizing: border-box;
margin: auto;
width: inherit; max-width: 90%;
height: inherit; max-height: 90%;
top: 0; bottom: 0; left: 0; right: 0; /* Force centering by pulling on all four corners */
border-radius: 100%;
}

.turning1 {
border-top:    20px solid rgba(0,0,127,1);
border-right:  20px solid rgba(0,0,127,1);
border-bottom: 20px double rgba(0,0,127,0);
border-left:   20px double rgba(0,0,127,0.5);
animation: turner linear 3s infinite normal;
}
.turning2 {
border-top:    20px solid rgba(127,0,0,1);
border-right:  20px solid rgba(127,0,0,1);
border-bottom: 20px double rgba(127,0,0,0.5);
border-left:   20px double rgba(127,0,0,0);
animation: turner linear 1.8s infinite reverse;
}
.turning3 {
border-top:    20px solid rgba(0,127,0,1);
border-right:  20px solid rgba(0,127,0,1);
border-bottom: 20px double rgba(0,127,0,0);
border-left:   20px double rgba(0,127,0,0.5);
animation: turner linear 1.2s infinite normal;
}

@keyframes turner{
from {transform:rotate(0)}
to {transform:rotate(360deg)}
}
</style>
</head>

<body>
<div class="container" id="background" >
 <div class="spincontainer">
  <div class="spinpaper" id="spinner">
     <div class="spintext"></div>
     <div class="turning1"><div class="turning2"><div class="turning3" ></div></div></div>
  </div>
 </div> 
</div>
</body>

</html>



Levels or Curves?

Things Digital Posted on Fri, May 31, 2019 20:06:41

Again, based on discussions in the Viewfinders club…

Once you get to the stage where you get your digital photos onto a computer and start working with “image processors” to make adjustments, a question one often hears is “what should I use – Levels or Curves?”. The Questionner is referring to different types of tool that can be used to adjust the rightness and/or contrast of an image. The Questionee’s standard answer is whatever suits you best”. Which is correct though not necessarily very helpful. I’ll try to elaborate on the difference here, without getting too technical.

All photo processing software tools are equal (though some are more equal then others), but they do tend to use their own names for things or operate in slightly different ways to what’s described below. However, the basic principles are the same, and some experimentation will help along the way (remember, digital bits are very cheap, but keep a safe copy of your original photo in case something goes totally west).

Brightness and Contrast sliders.

Most photo editors have two simple sliders called like this; usually right in your face so you can’t miss them. For a first approach they do what it says on the label (some have “Exposure” sliders as well). It is a bit of a blunt instrument though. You can increase the general “brightness” of the image, a bit like the volume control of a radio – you can make it louder (brighter), or quieter (darker), to taste.But then everything gets louder (or quieter if you turn the knob the other way). A good start but lacking some subtlety sometimes. If the music is quiet you may be tempted to turn the knob up a little more, at which point some hissing may become audible. Much in the same way, a “too dark” (under-exposed) image can be boosted up to the point that “noise” can become visible in the picture too.

To continue the analogy with a radio, the Contrast control is a little like a basic “tone” control found on some simple radios. Moving it changes the general tone of the sound (how the highlights sound), and by analogy, the Contrast slider adjusts how the blacks, greys and highlights are related.

The simplest of adjustments, and usually the first (and, to be honest, quite often the only) “tweak” on a photo.

Levels.

Moving up from a simple radio to a classic home “hi-fi” system, you may well find some extra controls – Bass” and “Treble”, and sometimes even “Mid” knobs to twiddle. Bass adjusts the low-end, darker sounds, treble the high-pitched brighter sounds, and Mid (if present) kinda gets freaky with the middle tones (it’s funny that way).

From our analogy again, the “levels” in your photo software will have one control for the “darks” end, one for the bright end and usually at least one for the mid-greys. And these too do what it says on the label. The Black control will control the level (yes) of the blackest parts of the picture, White the top end, and the mid-point control will let you shift the middle grey tones up (brighter) or down (you got it).

Still not the most accurate of instruments, but it’s certainly very usable.

Curves

This is where we go from the normal household hi-fi audio system to something more resembling a professional recording studio. At least as far as the “tone control” goes, this has now become a set of sliders controlling quite well-defined pitches of sound, giving very precise control of the amount of each one in the sound you hear. The knobs are usually sliders which, when lined up next to each other, can look like a nice, graceful curve (so they call them “graphic equalisers”). Yes, you get where we’re going here now, right?

The “Curves” tool in photo processing would probably be rather cumbersome if it had a slider for each level of grey to be adjusted. Instead, they allow you to define the nice-shaped curve (from which they calculate all the intermediate values required), by adding points along the curve that can be pulled up or down as desired.

Normally, curves are used to give fine control of the appearance of the different tonal ranges in the source image. You can boost (push the curve up a bit) or reduce (pull the curve down a bit) at different places along the histogram at will.

Pulling the lows down a bit and pushing the highlights up (or vice-versa) produces a slight “S”-shaped curve, sometimes referred to as a “sigmoid” (just to be geeky, I think), but which is very effective and intuitive for correcting many images taken in “difficult” lighting conditions.

You can also get quite extreme: pushing the “Black” end all the way up to “White” and pulling the White end all the way to Black produces a negative image. Keeping the “White” end at white and pulling down the middle of  the curve gives an interesting “solarisation” effect. Experiment, and observe what happens. It’s the only way!

Local adjustment

The above description applies changes to the whole of the image. However, most photo processing tools will allow you to apply any of the above adjustments to specific areas only. Often, a “mask” can be drawn by hand (usually shown as a contrasting colour, so you can see what you’ve done – though this colour itself doesn’t appear in the final image of course). More advanced software will also give you all sorts of tools to help draw very precise masks, fill large areas (e.g. the sky,…), etc. etc… Where the mask is painted, the adjustment will be applied, elsewhere not. This allows you to pick out one problematic part of your picture and correct it (face too much in shadow? Just brighten that bit. Here, I’ve darkened the building facades just to show the point).

Back in the days of “analog” printing, you’d use your hands or bits of card with holes cut out to “dodge and burn” the print (lighten or darken respectively) in certain areas, simply by casting a shadow on part of the print, or only exposing one area of the print for part of the exposure time. Tipping the hat to the pioneers of photography, the terms “dodge and burn” are still in common use in digital photo processing today. Some really good tricks like this will never die, I guess…



Picture Window Pro is now available free

Things Digital Posted on Wed, April 24, 2019 22:10:52

A recent discussion on our lively Facebook group highlighted a trend that seems to be growing – getting away from processed images andgetting things as right as possible “in-camera”. Still, the need for minor trimming of a few technical parameters, and possibly some local adjustments, is there, even in the purest of approaches: even with this trend, there exists a need for basic, no-fuss, cost-effective software, therefore.

A very long time ago, when I was looking for an affordable and usable alternative to Adobe’s already Gargantuan Photoshop (I talk of before the days of Lightroom – yes, the Earth had cooled sufficiently by then…), I trawled the interwebs and found the highly-acclaimed “Picture Window” programme, from the company Digital Light and Color. Back then (at version 3) it cost about €70 and proved to be very good value for money. DL-C is a small company, set up by photographers to make a photographer-friendly programme for quality processing of their images: I dutifully bought the upgrades until Version 5, which is still installed and frequently used on all the PC and laptops I possess. Now, at Version 7, it has officially been released as a free programme. I’ll describe my experiences with it below, which on the whole are Very Good, and now it’s free, you could hardly go wrong to just try it out.

While it offers the ability to handle RAW files, PWP is best used for editing JPEG, TIFF or other standard formats. Though offering an extensive pallet of quite advanced processing possibilities, it really shines for just the basic “tweaking” that may be needed on most images, which can be done very quickly indeed – it doesn’t require files to be “imported” in any way: you just open the file, directly from the memory card if you want. Common things like cropping, exposure, contrast, colour saturation, white balance are immediately to hand, work intuitively and give very good results.

A “mask” feature is available, which is very neat and useful. All adjustments can be applied to the whole image (no mask) or by using such a mask to locally control how much effect the adjustment has. It works like a paintbrush with soft edges, to “paint” an adjustment just where you need it to be, with some very handy tools to make creating these masks very quick and easy. I have often used it, for example, to lighten a face that’s a little dark from being in shadow, or even using teeny-tiny masks to accentuate highlights in the eyes…

It also has cloning tools, which are useful for removing bits and bobs that you may not want in the picture. It can also do composites of different pictures, or create layouts of several on a page. It also does something simply that many high-end programmes seem to find hard – make a nice, properly calibrated print without any fuss.

It’s no Photoshop, so don’t expect wonders of retouching or major manipulation, but I find that it is in fact a VERY handy programme to have around (my secret – most of the pictures that you have ever seen from me in the Viewfinders Newsletters have gone through it, if only just for cropping).

http://www.dl-c.com/



My Digital Workflow

Things Digital Posted on Wed, April 24, 2019 21:23:29

To try and launch a kind of learning experience around how to make photographs, I thought to describe my own “workflow” and see if this could identify some items for interesting and educational discussion.

Step 1. Take the pictures.

You could say that the processes are different for every single shot you’ve ever taken. For me, as probably for most, it means setting the camera to a basic set-up, from which any special needs can be selected without too much trouble. This may change during a day, depending on the lighting, indoor/outdoor, etc… but it’s a pretty standard way to work. A trick I use which may not be so standard is as follows. I generally favour Aperture Priority mode and set up the camera accordingly. I do take the trouble of  programming a set of Manual settings I can quickly switch to, that can be useful to “save the day”. Typically, settings for using a flash when the rest of the shoot is available light.

Step 2: Get the pictures off the camera.

For this, I connect the camera to my main computer and use the Canon “EOS Utility” to download the photos. You can of course take the memory card out of the camera and use a card-reader to copy the files, but I find that the Canon utility saves me a lot of bother: all orientation information about the shot is kept (portrait / landscape – something I had trouble with in the past), and the photos all end up in a logically named folder in a place I can easily find, without the need for any input from me (I’m lazy).

My computer is set up to automatically take a backup copy of any new files every day on a local drive, and also to my network connected server. This backup also saves the pictures I have worked on. Very handy. I don’t delete the pictures from the card until I next need to use it though – just in case!

Step 3: Selecting and Basic Adjustment.

I power up Capture One Pro, which uses my single, standard “Session” as a default. I don’t have the discipline to tag all my photos, making a Catalogue quite redundant for me. Using this one Session means I don’t have to  “Import” the images or any such step – I can just navigate over to the newly created folder with images and go.

Stepping through the pictures chronologically, I can quickly identify the one’s I’ll probably keep. I do the basic adjustments at the same time (exposure, colour balance, cropping, and usually add some “Clarity”), then give it one “*” if I’m happy with it before quickly moving on to the next.

Most of my pictures are delivered in big batches, so this works OK. If there are any I come across that are candidate for some “special treatment” (like B&W, a print or whatever) I may give it two “**”, just to make them easier to find again.

I have on some occasions used the “Auto” feature to set the baseline exposure etc…, but this takes a while to do on all images, and while it sets up a close reference point, it really doesn’t speed me up much, I find.

Notice I didn’t mention “raw” or “JPEG”. I happen to use raw, because I get a lot more leeway in the adjustments (especially in dark areas where noise could become an issue, or in tungsten lighting conditions), but that’s a personal choice. The same method works for either in Capture One Pro.

Step 4: Output the images.

As I use raw format, the images need to be processed to make them into jpegs. The same is true for any jpeg images that have been adjusted (Capture One Pro uses non-destructive editing – it doesn’t touch the original file – so any edited image must be “processed” into a new file to make it available). For this I have a number of “pre-set” recipes that serve mostly to allow me to quickly create different pixel-count images for different needs. I also have some with a watermark pre-programmed. Each “recipe” saves its processed images in a clearly named folder, in the same folder as the images they came from. I do have a few special ones that saves them somewhere more centralised, for “one-off” edits, or those “special” images with two “**”, should I need them. These would also be the candidates for printing, of course.

For saving JPEG images, I have created recipes for different fairly standard needs. They set the image size (in pixels) and compression factor. These can be to fit a box 400pixels each side, to use as thumbnails, to fit a box 1080×1920 pixels (for an HD-sized computer screen), 1600 pixels longest side for “every day” use (including Viewfinders newsletter), or “100%” for full-resolution images. Oh, and one that fits a box 1400 x 1050 pixels, for projection at Viewfinders meetings! 😊

So, I select all the “*” images and activate the batch queue, with the recipes I want to use selected- Capture One Pro will process several recipes in parallel. Don’t go for a coffee yet, though, because it actually happens fairly fast. As the images all end up in a special folder, it’s then relatively easy for me to upload them to my web-site for delivery, send them in to the Newsletter (hint), or copy them to a USB stick. Or whatever.

For printing at home, I tend not to use Capture One Pro directly (except for sporadic contact sheets etc…). It needs a lot of hand-holding to get nice results, I find. Instead, I use a fairly basic photo manager, and stick to using the standard Canon drivers that came with the printer. I usually get very good results that way. For printing at a service lab, I use 100% size (maximum pixels) and 95% compression factor JPEG. Never had a problem!



Deeply dippy … about DPI

Things Digital Posted on Wed, April 24, 2019 21:10:50

The world is unjustly full of misunderstandings about Dots Per Inch, or “dpi”, sometime also referred to as “pixels per inch” or “ppi” (but then my cool title wouldn’t work… 😊 ).

For my work (day-job or as photographer) I often get asked to “send the picture to me in high resolution – 300dpi”: the person asking often doesn’t seem to realise that this is a meaningless request. In order to comply, I then have to ask “how many inches will the picture be printed to?”.

Silence…

I usually end up just sending the picture with the maximum number of pixels I have in the image, which is often a very big file and certainly “overkill” for most uses (with a file from my Canon 5DmkII, which has 21MPx, a 300dpi print would be about 30×45 cms big – roughly A3 size).

One time, to make a point, I sent a “300dpi” file which had 300px on each side, which is of course the same as 300dpi (ppi) for a 1 inch (2.5cms) square print, but which looks rather poor when printed on an A4 page…

The moral of this sorry tale? There are a few:

  • Digital files don’t really know about “dpi”, as this refers to the physical size of a print. All they know about is pixels, and how many there are. The “dpi” data found in some digital files is calculated from: dpi = (number of pixels along a side of the print) / (length of the side of the print in inches) – literally “dots per inch”.
  • Start thinking about your image in terms of how many pixels it has. Some typical applications have typical numbers of pixels for optimum use. See the table below.
  • Learn how to re-size your digital pictures to give files with a suitable number of pixels. There are some tutorials on the Viewfinders web-site under “Resources” that can help with this.

Typical pixels needed for various uses:

 200 –  400 px highSmall web-page image / thumbnail
 900 – 1200 px highLarger web-page image
1050 x 1980 pxFull HD image (computer monitor / TV)
4200 x 7920 pxQuad HD monitor (but this is getting silly…)
1200 x 1800 px10×15 cms print
2500 x 3500 pxA4 / 20×30 cms print
3500 x 5000 pxA3 / 30 x 45 cms print
 900 px short sideVF newsletter, small illustration
1600 px short sideVF newsletter, large image



Capture One Pro

Things Digital Posted on Thu, May 25, 2017 18:20:20

Recently, I was asked to give an overview of my favourite imaging processing software at the viewfinders club. This is Capture One Pro. For this I gave a small demonstration of the speed and ease that images can be stored, sorted and adjusted. That sequence seemed quite popular (maybe because of the model! smiley) – it is:

Original image from camera. Not bad, but too much messy background.
Cropped a bit. Background still too messy for my taste, so …
Darken everything ….
Then use a large, soft brush to make a mask to bring up the subject… Not bad!
Make a variant of that in B&W – because I said so! smiley
Still just a little more trimming… Can’t quite get rid of that can top in the lower right… smiley
… So use a “healing” mask to brush it away. (I used the face from the other part of the place-mat to cover up the can top, though it’s almost invisible). Et voilà! smileysmileysmiley

(In real time, it took less than 3 minutes to get to a really presentable print. Capture One Pro rules!)



Scrambled Eggs and Hashed Browns

Things Digital Posted on Mon, May 01, 2017 19:19:51

This is something for the true geeks…

I’ve recently been upgrading my website (dafos.be) to be friendly for
mobile devices (using the “Bootstrap” library, if you’re into that sort of thing) and came across a trick I used to make a secured area for customers. It’s secure enough to stop anyone except a really dedicated hacker who actually breaks into my account, yet didn’t cost me an arm and a leg in high-security software to implement.

The problem with most cheap solutions you find on the hinderwebs is that they store the usernames and passwords as plain text inside the code that’s loaded with the page. It takes no more than “show source” in a web-browser to get a list of the users and passwords on that particular website.

So, I applied a bit of a trick used in my data modem days (remember those funny warbling sounds going over the telephone?) – a “scrambler” would be used to break up repetitive sequences of data that could cause the modem to essentially get it gloriously “wrong” and drop out. By similarly scrambling up usernames and passwords, they can be stored in an encrypted form. By doing the same scrambling when the user enters a name and password and looking for the same scrambled sequence in a list, a valid user can be identified while those absolute cads who’d want to break in to my website and steal my customers’ photos have a harder time.

I’d need a real cryptologist to check this, but I suspect that the scrambler I used is non-reversible (can’t run it backwards to get the original user/password out of it) which means that even if someone does look at the page source and figures out how it works, they still couldn’t recover valid user-names and passwords.

In fact, I suspect that the same crypto-expert would object to the term “Scrambler” and would probably choose “Hash” instead!

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