Wednesday, November 12, 2008

folding bellows

folding bellows video here

this link will show you how to fold a folding bellows
it won't show you how to make it - but that can be researched. I suggest paying attention and taking notes. there is no sound - besides, it's in there.

Saturday, November 8, 2008

printing - an introduction to color management

Printing – an introduction


Dpi: dots per inch

Ppi: pixels or points per inch

Resolution: defines the depth of detail an image can reproduce and is measured in dpi or ppi – dots or pixels per inch.

Saturation: defines the purity of color

Metemerism: The phenomenon that two color samples composed of a different mix of primary colors may look the same with some lighting and may produce different color sensations (look different) when viewed under a different lighting.

Primary Colors: those colors of a color model used to construct the colors of the pixels. For example, we use RGB – red, green and blue

ICC profile: A standardized data format to describe the color behavior of a specific device. ICC profiles allow your devices (monitor, camera, printer, scanner) to speak the same color ‘language’.

Gamut : the total range of colors (and densities) that a particular device can reproduce or capture.

Dynamic Range: is the total range of densities that a particular device can reproduce or capture.

Clipping: loss of certain tonal values usually found in the color or tonal limits of a color space. Usually some saturated colors are clipped to become less saturated colors.

Calibration: Adjusting the behavior of a device to a pre-defined state.

Profiling: Usually a two-step process, whereby the first step s to linearize the device (calibrate). The second step measures color behavior of the device and describes it with an ICC profile.

Soft-Proof: Usage of the monitor as a proofing device. For soft-proofing, Photoshop simulates colors an image will have with different outputs and will use the ICC profile assigned to show approx. how the image will print.


How many pixels or dots per inch do you really need?
Depends on a few factors
Type of technique (printer) used
PPI values you need will be roughly the same
The DPI values of the printers will change
• The resolution of your image may be 360ppi
• Epson brags that our 4800’s resolution can go to 2880 x 1440 dpi
What this means?
- You should not print an image at a higher ppi than the available resolution (dpi capability) of your printer.
- We print our files at anywhere between 300 – 360 dpi on the Epson 4800

Type of Paper used
• Rough, absorptive paper like newsprint will allow the ink to bleed a little (called dot-gain) and you must reduce the dots per inch (the resolution)
• If you use a good, smooth-coated paper you may increase your resolution and get a finer, more detailed image.
• Glossy or Luster paper will allow you reproduce even mor details than with matte paper or canvas.

Viewing distance:
o Viewing distance is important as the human eye tends to blend things at a distance and can only deliniate a certain amount of detail up to a certain viewing angle.
- If a photo is ledger or A3 size viewing distance is usually greater than that of letter sized images. Posters and banners – billboards and building sized images (if you were able to get close enough) would reveal that the resolution might have
- even dropped to 10 – 20 ppi.
Type of Printer Driver, Driver Settings and interpolation Used:
- For best results you should use a ppi value close to or even exactly that of the printer’s native resolution. Epson inkjet printers usually have a ‘native resolution’ of 720 ppi and a second native resolution of 360ppi.
o If you have an image with resolution that is close to either 720 or 360 ppi than you may not want to worry about the algorithm that Photoshop will have to apply to the image in order to make it bigger or smaller.
o If the in question is significantly larger/smaller you will want to choose (IN Photoshop – in the Image Size dialog box) to tell it how to best interpolate (resize) the image.
Your choices:
Bicubic Smoother: for Up-sizing or Bicubic Sharper:for down-sizing


Matching Paper with Subject and Inkjet Technology:

It’s recommended that you use paper that:
Matches the type of printing method used – inkjet printer
Works smoothly together with the ink and final print resolution
Suits the image subject
Suits your personal preferences

Paper Handling

Before printing:
Keep paper dry, in its original container if possible
Keep paper out of light, keep it clean and check any expiration dates on the box

Preparing for Printing:
Inkjet paper is sensitive to the oils on your skin so use cotton gloves when possible
Wipe the paper with a soft brush when you are working on your final prints – or use a blow brush intended for photographic film cleaning – be careful not to scratch the surface.

Handling for Printing:
Make certain you print on the coated side
Check if the printer you are using can handle the thickness or type of paper you intend to use – you can always look online to see what the manufacturer recommends. It is wise to do this BEFORE you purchase the paper.

After Printing:
Avoid contact with the freshly printed surface until it is completely dry,
Place a fresh print on a clean, flat surface avoiding bright light or/and sunlight
Drying time depends on the kind of inks used and on the media/paper you use.
Most inks dry within a few hours but you can leave it overnight just to be sure.
If you intend to frame or put your prints behind glass be sure to let them gas out or dry for at least 12 – 24 hours before doing so.
You could even wait a week….but really – do you ever have that much time?

Storing your prints:
Storing digital prints is much the same as for storing silver-based or other
photographic prints
Keep them clean, dry and when not on display in the dark.
Isolate the prints using buffered tissue papers that are acid free – good sources for this can be found on www.lightroom,com

Color Management for Printing

Different Color Models:
A Color Model defines the way colors are described in a technical way according the the Primary Colors.
Color Depth: this refers to how many bits you can work in. A 16-bit depth is able to differentiate between twice as many values as an 8-bit depth – which takes up more space (larger file) but also gives you more headroom when it comes to differentiating btwn color values.
It is recommended to use 16-bit depth when possible – it is a manageable place to work.
Most of the time when you output your image (print) you will have to do so in an 8-bit mode – but that doesn’t mean you have to work there.

16-bit mode – for working on files & 8-bit mode – for printing
sure, you can keep the image at a 16-bit depth – but that’s overkill as most printers can only output about 256 colors anyway.

RGB color Model:
All colors in RGB color model are created from the primary colors RED, GREEN, & BLUE.
This is the model most commonly used today in digital photography.
RGB is an additive color model – meaning that the sum of all three colors at 100% will add up to pure white….this is based on light, not pigment.

CMYK color Model:
This uses the four primary colors: Cyan, Magenta, Yellow and Black (K) is thrown in.
CMYK is a subtractive color model – all the colors absorb (subtract) a certain spectrum of light.
This is based on a pigment or ink model so it’s dealing with the colors that are reflected or absorbed by the primaries. If you actually added together cyan magenta and yellow it would not produce black with is where K steps in – it’s black added to the mix.

We do not use CMYK in digital photography – even though most printers are actually CMYK printers they convert to CMYK automatically from RGB so if you were to actually send or convert your RGB file to CMYK manually – you’d be doing some extra converting and lose some image – it’s just not a good idea.

Color Management – why is it important?
Color correction and color management are really where it all comes together – all of that hard work you’ve done can be undone if your CM (color management) is inefficient or not working for you – and believe me, you feel as though sometimes it actually is working against you…

The goal of color management is to ensure that the photo you view on your monitor accurately matches the print produced by your printer.

The challenge: to get your devices to speak the same ‘language’ – to match your camera to what you saw when you shot the picture, to get the monitor to match your camera and to get your printer (your final print) to match your monitor so that each time you print you don’t have to spend all of your time tweaking settings and wasting paper. That’s the goal anyway.

The solution: you need to determine the color characteristics of a device and to incorporate them when reading colors from an input device, or when sending color to an output device. Essentially, you put a ‘tag’ on color images that defines how the color values of the image are to be interpreted most accurately.*

Again with the language metaphor: you not only need to know what language your device is speaking but more accurately, what dialect so that the nuances, slang and colloquialisms are all understood and clear.

*The very nature of how the human eye (and we, the individual artists) understands, perceives and experiences color is subjective and so color management can never really be perfect or absolute – but you can control the amount of effort that goes into making each print…and that is valuable.

ICC profiles:
- An ICC profile describes a device’s color characteristics – the colors it can record or reproduce.
With the help of profiles, the color values required to produce a specific color on device A – like a monitor, can be translated to values that will reproduce that specific color on device B – the printer, as accurately as possible. A device’s color profile also describes the color gamut of
the device.

Color Management System (CMS):
- Is a set of program modules that mediate color translation among different devices.
- The ICC profiles (through the Color Management Module or CMM) will allow for translation between devices.
When a warning comes up that the destination of a particular image does not match the embedded color profile it’s telling you that the interpretation of color does not match and you will not get what you saw with one file with the next if you choose to convert it to the new color profile. While this is inconvenient at times it’s still best to allow your images to have embedded profiles – think of it this way – it allows you to at least identify what the ‘language’ is – even if you don’t speak it.

Color Space:
This can be very complicated – to be brief – we work in RGB 1998 because it’s considered best for digital photography and gives us a wide gamut for our images while working within the confines of the papers we usually will use.

For more detailed information please don’t hesitate to purchase or check out:
Fine Art Printing for Photographers by Uwe Steinmueller and Juergen Gulbins a publication of O’Reilly books and rockynook press, published in 2007-2008