When is B&W really B&W?

BetterSense · 08-18-2008, 01:49 AM

I have Gimp and digikam. Ok. So I shot my first roll of B&W yesterday, BW400CN. I got the picture CD back from Target and some of the shot had a distinct brownness to them.

So, why are they brown? Is it target's development, scanning, or is it the film itself? I could scan the film myself to cross-check.

I don't have calibrated equipment, for one thing, but sometimes B&W photos look kinda bluish on my monitor.

Is there a way to digitally make a photo like completely black and white? Like NO color? Is this done by simply sliding the saturation down to nothing? If so, then regardless of how they look on my monitor, I can know that they are actually black and white. Although I'm still not sure if that's what I should really be striving for, or if I should leave them the way they come from target.

pasipasi · 08-18-2008, 01:59 AM

The browness is probably from the scan. You can quite easily desaturize the pics with Gimp.

BetterSense · 08-18-2008, 02:00 AM

ok. So if I desaturate, they are truly black and white?

Because they really look blue tinted in my monitor. Especially right after desaturating from brown.

*khardur* · 08-19-2008, 08:51 PM

If you desaturate them and then they look blue, then I think you need to calibrate your monitor.

If you already shot them on BW400CN film, then simply desaturating should be fine. If you wanted to convert color images to B&W, desaturating will most often give you a flat look.

If you have a digital camera and want to try a free color ->B&W converter that mimics using different colored filters with B&W film, try the B+WPlus filter from cybia. (link here).

It's freeware, as are many of their plugin filters. But of course you are shooting film, and black and white at that, so for these plugins you'd need a color digital image to start.

*Clicker* · 08-20-2008, 07:41 AM

It's Target's channels setup for "standard" C-41 processing, try a pro lab. Consumer labs will print them Sepia toned. (actually pro labs will too unless you specify B&W which is an upsell)

colour2B&W using GIMP

BetterSense · 08-20-2008, 08:00 AM

yeah I think digikam lets you convert to B&W while mimicing different lens filters. I tried it with my BW400 scans and all the filters were identical...took me a second

the sepia doesn't really bother me, it's just that some of them are more sepia than others.

*Nesster* · 08-20-2008, 10:51 AM

It is the scanner's auto wb that gets fooled. As everyone says, if it bothers you just desaturate.

With B&W film, you have to use real filters at exposure time. After that, color info is not stored so using a red filter to get deeper sky won't work! On the other hand, when converting to b&w from a color image, the time to apply color filters and shifts is during the conversion.

BTW, I don't believe that pure b&w ever existed, or rarely if it did. All photo papers have some shading or tinting - warm or cold - and most printers used this to advantage. Subtle maybe but there. Often tonality shifted slightly with the light value in the print.

If you're ink jet printing, adding a bit of toning to the blacks and greys will give you a better print. Otherwise the print driver will be struggling to concoct a 'pure' black/greyscale, which usually is very difficult for it.

graphicgr8s · 08-30-2008, 09:45 PM

More than likely it is the scanning. Even though the film is BW the scans most likely are still rendered as color. The lab scans in RGB and is not going to change over to grayscale for one roll of BW. Check the channels of the file and more than likely it would be RGB. It should be grayscale. Desaturating will remove the color but won't make it grayscale, which is what you want. Printing a desaturated photo will still add a touch of CMY to the image. Printing a grayscale image will only print shades of black.

marcdsgn · 09-10-2008, 09:53 PM

Keep in mind, genuine black-and-white prints use a paper embedded with a photoreactive silver formula that turns true black (and various tints of black, depending on the level of light received). Modern photoprinters combine various percentages of four separate dyes that create cyan, magenta, yellow and black tones to simulate all colours, including greys and blacks.

So even if you submit a grayscale image for print, the printer will translate all grey tones as combinations of all four colours. Provided the printer is well calibrated (rare!) your print will still resemble a genuine black and white image. But if the calibration is off (most likely!) there will be evidence of colour imbalance, causing your image to tint toward bluish or reddish tones.

Why doesn't the photoprinter just utilise the black tone when printing black-and-white? Because each dye is partially transparent, so it will not produce a full-bodied tone by itself. The other three colours are required to build up its opacity.

graphicgr8s · 09-14-2008, 08:06 PM

Originally Posted by marcdsgn

Why doesn't the photoprinter just utilise the black tone when printing black-and-white? Because each dye is partially transparent, so it will not produce a full-bodied tone by itself. The other three colours are required to build up its opacity.

If you spec it as grayscale or use only the black in a CMYK file the printer won't use all 4 colors. And some units use six colors (hex printing) also known as Hi Fidelity color.
As for the dye being transparent well so are press inks and you can print a straight black which is just black or "rich" black which adds cyan magenta and yellow behind the black for a deeper black. However a grayscale image setup correctly will still only print black.
If your program has an info pallete make sure that you have no less than 5% black in the highlights and no more than 95% in the shadows. And there shouldn't be any other color if your in cmyk.
Your monitor is still converting it to RGB so you may still not see a true grayscale but the info pallete will tell the true story. (Or you could just look at the channels and see if anything is on the CMY channels)