Print the BlackAndWhiteExtents.jpg image using the media/profile setting that you want to evaluate.

In the dark side of the step tablet locate the black step where there is the first change from the full black stripe.

The low aim point will be the adjacent darker step.

Often profiles bottom out at 15-20. An image targeted at a low aim point of 0 will be crushing 15 points of shadow detail.

In the light side locate the step where there is no difference. The high aim point, Zone VIII is the adjacent darker step. I like to be laying down ink on Zone VIII and not on Zone IX values. This is usually the difference between 253 and 255. I will try to have a few twinkles of Zone IX that is pure paper white.

Armed with these two numbers images can be more precisely targeted to a material and profile.

Targeting the Image

Use the threshold layer to target the image.

Add a Threshold layer over a Levels layer on top of the stack of layers.

• Set the Threshold level to the low aim point value, the image will be mostly white.
  Adjust the low output of the levels layer until there are a few spots of black on the white field. These regions will be full black.
• Set the Threshold level to the high aim point value then adjust the hi slider down until a few spots of white appear on the black field. On a high resolution image it is wise to zoom in some and check. Hi aim point targeting will not work if there is no white value in the image however usually there is a white value.

Download Test Image

Tags: extents,tablet,step,printing

I have been favoring prints made on canvas materials for a number of reasons.

People like them much better then framed photographs, they are highly viewable as glass-less prints and are very light weight.

However as a photographer stretched canvas was all a mystery to me. I have gone through a learning curve to be able to produce canvas prints. While the requirements for photography is similar to stretching canvas for painting photographs want a little less tension. 

I have been using the LexJet Instant Dry Satin Canvas with a custom profile on my 12 color Canon 8300 and have been getting excellent results.

Here are the steps that I go through to produce a print. I usually make several strainers at a time to conserve my efforts.

Making Strainer Bars 

Tools: 

• Table Saw
• Miter Saw
• Handheld Orbital Sander
• Hot Glue Gun
• 4 Pony Clamps
• Drill with 1/16 bit and 1/8 bit

Materials: 

• 1x2 Douglas Fir with rounded corners 
• 4d finish nails 
• Small Screw Eyes 

I cut the strainers myself out of 1x2 Douglas fir round cornered stock. I use a table saw to rout out the inset and a miter (chop) saw for the corners.

If you don't cut the inset on the stretcher you will see the topography created by the inside edge of the stretcher touching the canvas. I cut  the insets first in the 8-foot lengths of 1x2.

After cutting the inset I sand the raw routed stock to smooth and lower the inner edges of  the inset cut. 

The stock is then cut with the miter chop saw to be the correct lengths with 45 degree mitered corners. 

 

 

The pieces of routed and mitered 1x2 are held together with 4 Pony clamps while I liberally hot glue the corners and cross pieces. After the glue has cooled slightly I pull the excess off, usually as a single piece. Pre-drill the corners with the 1/16 bit and nail with the 4d finish nails. I use 2 nails in the corners for smaller pieces and three in larger pieces. 

 

 

 

I put screw eyes in either side of the vertical bars. These will hold a piece of picture wire to support the unit on the wall. The screw eyes are located about 1/3 of the way down from the top. They are drilled with the 1/8" bit with a collar to prevent it from coming through.

Once the stretcher is assembled I go over the front carefully with the sander to insure the lip and corners are smooth where they will touch the canvas.

On my 48" pieces I put one cross piece in the middle. The 72" gets two cross pieces and the 96" gets three. These are long narrow images. Larger rectangular pieces need cross braces to prevent the bars from bowing inwards from the pull of the canvas. 

 

The screw eyeys are set with a special tool for doing scew eyes, its very kind to your fingers.

The other option to manufacturing strainer bar is to buy pre-made stretcher bars. They are nicely made but rather overpriced. Stretchers can't be cut to length due to their dove tailed corner design. If you are doing one print buy them and smile :)

If you want a lot of big prints making your own strainers works out to be very inexpensive. 

 

Print Master Layout 

My prints have corner crop marks, a studio chop mark and show my copyright and edition type on the border of the image.

As these images have a certain amount of overwork the crop marks are invaluable to getting the print on the stretchers with the exact cropping. This is very helpful when you are not the one stretching the canvas as it makes your cropping very clear to the framer. 

I have been using doug fir 1x2 to make deep strainers this measures 1 3/4 deep. The print is formatted with 2" of overwork on all sides as shown in these illustrations. The 2" of print overwork allows the image to lap around the back of the strainer bars. 

The print is wrapped so that it completely covers the edge of the 1x2. The image are extends slightly onto the back of the sstrainer bars. 

As is the case with most photos I don't have that kind of overwork in the original. Simply clone brush the overwork onto a layer in the print master. This allows for a very nice looking frameless glassless presentation. 

I set my masters up to 180 DPI at size and find this resolution to be fine with canvas prints. Canvas supports less detail then smooth papers so you don't notice the slight limitation of the 180 DPI resolution.

I have tried masters with higher resolution and don't really see the difference in the print. This is especially true at normal viewing distances for larger prints. 

I let prints dry for 24 hours prior to spraying with giclee varnish. The print is then sprayed with a giclee varnish like the Breathing Color Glamour II Varnish and drys for another 24 hours. More recently I have been producing unsprayed prints and getting a good result. I think the emulsion technology is improving for canvas media types.

Stretching 

Tools:

• Electric T50 staple gun
• 6mm T50 staples
• X-Acto knife with #11 blade
• Cork backed metal ruler
• Cutting surface
• Soft cloth
• Picture wire 

I use an electric staple gun with 6mm T50 staples and a pair of Fredrix Stretcher Pliers to stretch and fix the print onto the strainer bars. 

I trim the print to have 1/2 to 3/4" white borders in addition to the 2" of image overwork prior to stretching. This is done with an X-Acto knife with a #11 blade and a long cork backed metal ruler on a cutting surface. 

The work area is then covered with soft cloth. I have several fleece blankets on which I stretch prints. This is important as the canvas can be damaged easily during stretching. 

The print is gently marked on the back with a soft lead pencil to indicate the crop marks. This is done face down on the cloth covered surface. The crop area is lightly traced onto the back of the print in pencil. Be gentle.

Orient the assembled strainers with the inset down on the back of the print and gently fold the canvas up on each side to check your positioning. Adjust strainer position as necessary. 

Make sure the top of the stretcher is at the top of the print. I usually mark the top of the stretcher when I build it. 

With the print in position fold up one side of the long dimension and place a single staple in the middle on the back of the bar.

Go to the other side of the long dimension and pull the canvas in the middle with the pliers until it forms a ridge down the middle. Place another staple to hold it taut.

Don't go overboard with the tightness but there should be a noticeable ridge in the center of the canvas running from staple to staple. 

On the short dimension gently pull in the middle and place the first staple. Go to the opposite side and pull with the pliers until there is a cross shaped ripple in the middle of the print. 

 

Working on the long dimension pull gently on one side and put a few staples on either side of the center staple about 1 inch apart. Then go to the other side and pull with the pliers opposite the staples you put in the other side until the canvas is tight and smooth. Place staples opposite the staples you added to the other side. Repeat this process on the short dimension of the canvas. 

Repeat this tightening going back and forth until you come to within a few inches of the corners on all sides. Do not staple closer then 2 inches to the corners yet... 

If you have a nice amount of tension you will hear a tympanic sound when you gently tap the middle of the print. In other words it will make a drum like bungggggg and then ring when you tap it. If it goes thud with no musical ring it is a little too loose. 

If you over pull with the pliers you can crack the emulsion and dye on the canvas. I have yet to do this but I heard it could happen. 

The corners are a little tricky but I think the pictures will make it all clear. I fold the corners so that the fold is on the top and the bottom of the unit as the edges are what is generally visible. This is a little different from the traditional fold which is visible on the sides of the print.

First gently fold the corner excess going straight out from the corner. I smooth the fold with my fingers to create a crease. 

 

 

 

 

Fold the resulting triangle towards the top or bottom of the picture and press it against the stretcher to gently bend it in that direction.

 

 

 

 

Fold the end of the triangle over on the inside. 

 

 

 

 

 

While pulling with your fingers on the corner fold it across the back of the stretcher and pull it tight. Use a staple to hold it in place. 

 

 

 

 

Then I fold the edge so that it has a 45 degree crease and press it against the back of the bar, use a staple diagonally across the fold to hold it in place.

 

 

 

 

One more staple completes the corner. I then will pull the canvas and staple it in the 2 inch area between the corner and the part that is already stapled. 

This process is repeated for all 4 corners with the folds going onto the top and the bottom of the piece. I use this corner folding style because it leaves the sides with smooth folds to the top and bottom rather then a dark shadow inside the top and bottom folds.

Tags: canvas,stretch,stretching,strainers,gallery,wrap

I have been trying different methods for the control of mid-tone contrast and have arrived at this method which works well.

After printing many outside files and all of my files I have learned that even a color calibrated monitor is not the same as a print on paper.

Initially I was in the “it’s me not you” group where I found the PDI Test Image printed very well on my custom profiles but my files were uniformly over-scaled. The shadows in my files were overly dark and blocked at the lowest levels in a print. All these files looked good on the monitor vis a vis the current level of contrast in contemporary work online. I downloaded a few files from other artists that were popular and printed them. Same result.

When I did a thoroughly non-scientific spot meter reading of the values 15 and 255 on my monitor I found it had a range of 6 stops. A typical print has a reflective density range of a little less the 5 stops.

As I looked at the firehose of photos on the internet I could see a commonality in the minimally processed images. The images were all dark in the shadows and low midtones, much of the greenery was dark and not very green and the shadows on grass and trees were very blocked. Many of the images had clouds that were very ill defined in the highlights. Full sunlight was rendered poorly with deep shadows and blazing highlights.

I had to downgrade myself criticism to “it’s not me it’s everybody”.

I perceive that the reproduction curve of the monitor is different from the printer. By this I mean that the monitors show far more shadow detail and render the low midtones lighter than in a print. This has to do with the gamma of the monitor which affects how midtones are rendered.

I calibrate my monitor using an eyeONE sensor and DisplayCAL. DisplayCAL is an open source profiling software that supports most sensors using the ArgyleCMS engine.

Download DisplayCAL - https://displaycal.net/

The Magic Lantern Effect…

With film we would always look at transparencies on a light table and marvel at the color and contrast. It didn’t go much further than that because offset lithography would usually kill anything and the internegative to ‘C’ print workflow was worse. An ‘R’ print on Cibachrome had good contrast but still did not represent the light table experience and crushed the already challenged shadows in the transparency.

This was the Magic Lantern, 70’s style.

Trans-illuminated high contrast media which looked good and reproduced poorly without heroic efforts.

Fast forward 20 years and we have the Magic Lantern 2019 style.

A backlit phosphor display with a fairly high contrast ratio… Different day, similar problem.

In these conditions it is all too easy to “get on the gas” and to overrun the limits of the print while looking fairly acceptable on the monitor. It is really a matter of learning what a good print looks like because you can get a range of renditions which look “acceptable” although some will print well and others… less well.

In Short…

What looks good on a monitor or light table may not reproduce well due to the new age Magic Lantern effect of the monitor.

Viewing this grayscale with values from 0 to 18 clearly shows the monitor displaying readable values below 18 the bar on the bottom is black (0).

Aim Points…

If you perform the Profile Extents target test on your printer/media/profile combination you will find that in your print the lowest recognizable value is between 15-20 and the highest between 250 and 255. You can skip this if you like, use my numbers and be quite close.

Aim points are the digital densities that we will set as the highest and lowest values in our printer ready file. I have yet to examine a profile that renders values below 15 so that is a good rule of thumb for a low aim point. Most profiles stop laying down visible ink in the 253-4 range

Low: 15
High:253

If your output image has values below 15-20 they will not be rendered in a print. This also will cause all of your shadows to be noticeably darker.

Properly targeting the extents of the final master for the desired output process is the first step towards better prints.

In the raw smart object I am happy if my shadows are above 0 and my highlight is 245.  This allows me to adjust the range of my raw pixels to meet my aim points of 15 and 253ish. It is important to allow this headroom. If you expand the contrast range of the raw file to hit 0 or 255 you will be losing values.

The Presets…

After months of trying different settings I found a fairly anti-intuitive pattern that got maximum detail and separation in the highlights while boosting up and defining the low zones.

I made these settings into an ACR Preset Group that you can download and install. This greatly expedites the contrast scaling process.

The benefits of using the Contrast preset is that it pulls back the highest highlights creating more separation in the high highlights while bumping up the midtones. In the scaling process I use most of the dynamic range 10-245 and validate that using color samplers in my raw smart object.

I am always trying to get more light into my images and this has allowed me to render the midtones lighter then I was before.

• Contrast-xx
  • Sets Highlights, Shadows and Whites into a V shape -20, 20, -20
• Curves-xx
  • Sets the curves dialog into a compensated curve of varying depths.
• Exposure=xx
  • Sets the exposure slider.
• Clarity=xx
  • Sets the clarity slider.

Install the Presets...

Download acr-contrast-scalers.zip

Install the contrast scaler preset group in Photoshop. It is Photoshop and LightRoom compatible.

These presets change only specific settings so that they can be used cumulatively. There is a preset at the top called 00 Clear. This preset will clear the Highlight, Shadow, Whites, Curves, Clarity and Exposure. 

Photoshop

• Download the file acr-contrast-scalers.zip
  • Dont unzip the file as it will be will be loaded as a zip by ACR.
• Open a raw file in Bridge or Photoshop, ACR will appear.
• Select the Presets Tab
• Click in the three lines on the right to open the local menu.
• Select Load Settings…
• Navigate to the file acr-contrast-scalers.zip and hit Load
• The new preset group will appear in your menu of preset groups

Lightroom

• Download the file acr-contrast-scalers.zip
• Open File -> Import Profiles & Presets
• Navigate to the file acr-contrast-scalers.zip and hit Import

Scaling an Image…

My initial goal is creating an opening color and contrast grade to provide a starting point for editing.

Adjust the color balance to taste. Set the white point and tint either by using the gray eye dropper or by selecting the appropriate white point then waving the tint back and forth to find the magenta->green balance point.

Open your raw file in ACR and select the presets.

Start with the Contrast…

Use the Contrast preset first. If further reduction is needed use the Curves in conjunction with the contrast preset.

Wave your mouse pointer over the Contrast-xx settings. You will see the image get darker and flatter. When it looks good click on the preset. The click makes the setting change to the presets value. As you make the image flatter it will get darker because the overall scale of the image is being compressed.

Makeup the Density…

When you pull the highlights down and lift the low midtones your image will get darker and flatter. Use the Exposure presets to add some makeup gain.

Wave the mouse over the Exposure presets until you have good looking highlights. When it looks good click on the preset. I put out a color sampler on the main highlight and look for it to be around 245. The numbers will work if the main highlight was white in your original image. Some images do not have a white value. In that case it calls for a visual evaluation of the highlight density.

Revisit the Contrast and Exposure…

Return to the Contrast and adjust further, if necessary, cycling back to the Exposure as needed.

If you get to the Contrast-100 setting and the image still has too much contrast start on the Curves presets and reduce contrast further as necessary.

Pump up the Detail…

Once a reasonable scale has been achieved add some clarity to further enhance mid-tone contrast.

I use NIK’s Viveza and will commonly add in some structure to further firm up the midtone details.

Load as a Smart Object…

Open the raw file as a smart object in Photoshop. This will allow you to further adjust the image non-destructively.

Locate the Highlights and Shadows…

• At the top of your stack of layers.
• Add a Threshold layer
• Wave the setting on the Threshold around 250 to find the highest highlight.
• If it is not specular or blocked put a color sampler there.
• Blink the Threshold on and off to see the image regions that it delineates.
• Wave the Threshold setting around 15 to find the lowest shadow.
• Put a color sampler there.
• Blink the Threshold on and off to see the image regions that it delineates.

Target the lowest Shadows…

• Add a Levels layer below the Threshold layer
• Set the Threshold layer to 18
• You should see a white field with areas of black.
• If there are areas of black
  • Adjust the Levels->Output Level->Lo to 15
    • This moves your shadows up so that they start at 15.
• If the image is all white.
• Adjust the Levels->Low slider up until you see some areas of black.
  • This moves the shadows down to hit 18, full black.
• Blink the Threshold on and off to see the image regions that it delineates.

Target the highest highlight…

To do this we must first evaluate the highlight. If it was white in the original scene its very easy. Simply adjust to the high aim point and smile. If that is not the case you should adjust the highlights visually.

• Turn on the Threshold to use the numbers, it should be off for a visual adjustment.
• Set the threshold to 250
• In the Levels layer set the high slider until the highlight is in the low 250’s.
• The image will appear as all black with specks of white.
• Blink the Threshold on and off to see the image regions that it delineates.
• This can often reveal the one hot spot that is preventing you from making the entire print lighter.

There are many other settings in addition to burning and dodging that you can add in to finish an image and they can be added to taste to complete your post cycle…

 

Tags: contrast,printing,rendition

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