Curves by Intuition (and some experience)

Energized by the good fortune of being able to set up a workshop this summer on a beautiful lake in western Maine, I found the courage to test my understanding of compensation curves used to create digital negatives.  The mountain spring water may be better nourishment for my body (and spirit?) than the city water on the university campus, but the radically different chemistry in the water liked to wash out anything in my images that was less than 50% black.  The standard solution for this problem would be to print a step wedge, analyze the resulting print, and create a correction curve that will stretch the tonal scale to compensate for the odd UV blocking properties of inkjet negatives.  But, this time, I decided to do something less rigorous.  With each image, I manipulated the compensation curve by estimating how much darker/lighter different segments would need to be.  This practice removed many steps in the editing process and forced me to visualize the entire workflow from Photoshop to real printing in the wet darkroom.  After making some big mistakes, I started to get the hang of it, and developed some unique curves for each image.  

For the sake of instruction, I ran an experiment in which I applied some of the curves to images for which they were not originally made.  This made for an interesting comparison that reveals what compensation curves are doing.  Below you will see an image chart.  Each row of pictures corresponds with the curve that was applied (screen capture of the curve at the top of each column).

(click on image to view larger)

The image below was an interesting challenge because most of the visual information exists on the far ends of the tonal scale.  Cyanotype is already a high-contrast process, and this high-contrast image meant that the compensation curve had to extend both sides of the tonal scale and flatten the center.

http://artandwater.blogspot.com/2012/08/12-different-cyanotype-tones-compared.html

Photopolymer Graveur Curves Preview in Photoshop

this is just the beginning (because I am just beginning)...
below is the original digital image collage, converted to grayscale, but otherwise untouched/unadjusted

photopolymer graveur (aquatint, "safe" etching, whatever you call it) will drop out values above 80% and below 20%. In other words at those points the value will go right to black or white. So, the grayscale really only runs between the two, in the middle ground, and is not subtle at all towards the end of the scale. (I have been told this is mostly true for the original Photo Graveur, and had to be addressed. Difference in this process is that most of the adjustment is on the computer and not the development process)

I have seen a couple of curves claiming to solve this issue, but they (in my opinion) only work at the cost of some variety in the middle of the scale. I suspect this is because they are trying to bring up values that are not there.

The best thing I have discovered (to date) is the simple idea of getting a reliable preview. No matter how much you adjust your image, it is difficult to guess how much information will be lost. So, when you think you are ready to go, I'd suggest adding on more adjustment layer, and moving the sliders over from 0 to 20, and from 100 to 80. Check out the results...
below is the adjusted image: it is the first (above) image, with the curves adjusted at 20 and 80 as a way for me to preview my results from the polymer plate.


below is the actual printed image from a KM73 photopolymer plate.
There is a bit of information loss in the scan, but this is a pretty representation of what it looks like.


To clarify:

Top image is the original, and the one I printed on a high quality transparency (Pictorico), and used to expose the KM73 photopolymer plate.

Middle image is the top image, with an adjustment layer (Curves) over it, sliders moved from 0 to 20 and from 100 to 80 to get a preview of how the image will look from the KM73 plate, knowing that information is lost above 80 and below 20. It is only a way to get a sort of soft proof, to make sure I am on the right track.
No matter how I adjust the image before printing to the transparency, I want to do this preview before printing to see if it will be satisfactory.
BE SURE TO UNDO THIS STEP BEFORE YOU PRINT!!! It is a preview technique only.

Bottom image is printed from the KM73 polymergraveur plate onto Rives BFK white paper with Graphic Chemical Vine Black etching ink.

Not much "Art" lately, but plenty of art

A friend of mine made a funny comment to me today. He was suprised that I didn't know all about fontface.com and some other pretty basic graphic artist things. He said, "you're an artist and you don't know about fonts?" Sure, I know about fonts, but I think that he had a misunderstanding of my artistic training. When I got my undergrad degree, the user interfaces for graphic arts on computers were still fairly tech-heavy and awkward. Add that on top of my interests being messy, thick paint,and it's pretty easy to understand why my personal art world is quite different from how the graphic art world has grown over the past decade.




http://www.cafepress.com/artandwater.110921958


I took a Photoshop course in 1993. It was really frustrating back then, but I managed. I am forever grateful that I took the course because I have found myself using the program more and more every year.


Lately I have been making an effort to play a little bit of "catch-up" and really diving into the computer world. Of course, my twisted desire for a genuine, (and often complex) understanding of things will lead me into some frustrating corners. But, I'm sure I'll come out of it with a good understanding.

(At the very least I'll have some cool images for tshirts. Nothing wrong with that!)Women's Tshirt