Embed Size (px)
MegaVision Monochrome a comparison to film and color digital capture. MegaVision MonoChrome E3, E427, E4. - PowerPoint PPT Presentation
MegaVision Monochromea comparison to film and color digital capture
MegaVision MonoChrome E3, E427, E4
In Section 1, we’ll take a look a the compromises of color digital capture, converted to grayscale. In the Section 2, we’ll take a look at monochrome capture compared to shooting black & white film. In either case, MegaVision mono-chrome is visibly superior.
Section One We’ll start our comparison to color digital capture converted to grayscale. Color capture isn’t really a color capture, it’s a monochrome capture through color filters applied to the sensor. This capture is known as a luminance capture.
This luminance capture has an R-G-or B filter applied to each pixel. As such, these filters have a traditional filter factor, or amount of light needed to equalize the density of the filter. With no color filters, monochrome sensors have a higher base ISO than Bayer patterned sensors. MV Mono sensors are 200 IS0.
On single shot cameras there is a need to capture the detail, or luminance of the picture. There is also a need to capture the color (chrominance) of the picture.
Although both chrominance and luminance come from the RGB pattern, the fundamental problem in the compromise of shooting digital color resides in the Bayer color pattern.
As it turns out, we humans have eyes that are composed of light sensing components called rods and cones. Rods (120 million on average) are far more numerous than cones (6 to 7 million) on our retina. Rods perceive luminance (detail) and cones perceive chrominance (color, hue, and saturation).
Not surprisingly, color sensors are configured with more pixels containing large contributions to luminance (Green), than those that have smaller contributions to chrominance (Red and Blue).
This cube represents the cube of bicubic
In a traditional Bayer pattern, the most common color filter matrix used today, half of the pixels are green, a quarter of the pixels are red, and a quarter are blue.
This Bayer pattern distribution is practical because green pixels contribute more to luminance (59%), compared to red’s contribution (29%) and blue’s contribution ( 12%) to luminance.
Disparate Bayer luminance contributions to the detail of the image are integral to the compromise of digital color converted to grayscale. Channel mixing can help with adjacent tonality but it doesn’t help mitigate the fractional luminance contribution of red and blue filtered pixels.
Black and white images from color sensors are problematic because the detail is compromised-- not all pixels have good contribution to luminance. On a monochrome sensor there’s no color filtration, so every pixel contributes 100% to luminance.
MV Mono E4 (top) vs MV Color E4
There are more problems with color sensors, which involves the file developing interpolation of the Red, Green, and Blue channels. Due to the Bayer pattern distribution, Red and Blue pixels are undersampled when compared to the green pixels.
Even though there is only one color at every pixel site, the generation of an RGB file from the luminance capture requires the making of the two colors not present at each pixel site, so that there is a full layer of pixels for each of the Red, Green and Blue channels.
This development is not without compromise and different developing converters have advantages and disadvantages embedded in their developing action. Color aliasing errors are one of the resulting products from developing the luminance capture.
Sharply focussed Color Aliasing Errors
Many dSLR camera companies believe that it is helpful to mitigate some of the developing disadvantages with a diffusion filter applied to the sensor, to smoothen the aliasing artifacts that are generated when a lens is sharply focussed on finely detailed reflectances.
Low pass optical filters blur the aliasing errors but leave the pictures not truly sharp.
Because monochrome sensors don’t have color pixels, they don’t need the low pass filter. Without the color filters, there’s no need to develop the pictures and without developing there are no aliasing errors.
Comparison of MegaVision Mono to B&W film.
Shooting B&W film has been seen recently as the “fix” for digital color, converted to grayscale. The problems with digital color may seem to remedied by going back to the old standard of shooting film. While shooting B&W film does solve some of digital color’s capture problems, there are other problems inherent in film shooting that can’t be easily overlooked. Let’s take a look at what they entail.
Optical imaging errors in the highlights.
The characteristic curve of film response
Spatial resolution. This is perhaps the most easily demonstrated compromise of film shooting. Just looking at the detail in a T-Max 100 or Tri-X Pan frame will reveal a discrepancy in resolveable detail.
1:1 image areaMV Mono
Because the film is the limiting factor in rendering spatial resolution, we can’t (and we wouldn’t) shoot the same image size of film vs digital. Obviously, we’d shoot bigger film. How big do we have to shoot to get equivalent results?
As it turns out, we need to shoot almost four times the image area to get similar results, and the film still isn’t quite as good. The following images are 36mm x 36mm MV Mono and 60x72mm TMX 100 scanned with a Flextight at max res.
E4 Mono RZ vs TMX 100 RZ 67 captures
E4 Mono @ 200% vs RZ TMX 100 @ 100%. Equivalent res; notice high values deterioration due to film grain.
E4 Mono @ 200% vs RZ TRI-X 320 @ 100%. Compromised res due to film grain and poor transition to highlight
due to light scattering in heavier densities of silver.
As we have seen, it takes quite a bit more film image area to be comparable with digital monochrome. While shooting bigger film is easily accomplished, handling the bigger camera is not as easily accomplished.
For most photographers, 6x7 cameras are tripod only devices, which typically forces a different vision and a different relationship with the subject matter.
It is practical to note that while photographers have eschewed TMX 100 for shooting scenes to be rendered with enlarging paper, it has demonstrated a much more linear response to light than traditional films and is therefore superior as a scanning intermediate. It is however, demonstrably inferior to a properly exposed and “developed” monochrome capture, especially in the transition to highlight, where light scattering through the heavier densities of silver cause a decrease in local contrast. This phenomenon is exacerbated by the modern T grain emulsions, whose grains overlap other grains in the emulsion.
Film’s characteristic curve has defined the professional shooter’s lighting skillset. Boosting the contrast in the lighting for film’s low end has included mirrors, hot cards, fill flash and other work-arounds to film’s lack of response and adjacent contrast in the shadows.
In the highlight, shooters have used large light sources to keep transitions smooth and specularity under control.
These workarounds are used to control important transitions in the “toe” and “shoulder” of film’s response; illustrated by the familiar characteristic curve:
Because digital capture counts electrons arithmetically, there is no “toe” or “shoulder” in the transition from shadow to highlight unless the developing technician puts them into the remap. For this reason, digital capture allows some freedom in lighting that film does not recommend.
It might be inappropriate not to discuss the post production sharpening capabilities of MV mono vs B&W film. As can be seen in the film scan reference files, the grain structure of film engenders an obstacle to critical sharpening that digital monochrome capture does not suffer.
In summary, MegaVision Mono performance is demonstrably superior to both color digital capture converted to grayscale, and to B&W film and scanning. While we did not discuss B&W film and traditional enlargment, the Mono capture is superior to the traditional B&W workflow, because of the toe and shoulder response of film and the optical rendering of the print.
Compared to color digital converted to gray, lack of Bayer pattern filtration allows:
Increased native ISO.
No developing artifacts because there’s no need to develop.
No need for low pass optical filter.
Superior luminance; 100% contribution from each pixel.
Compared to B&W film:
Increased spatial resolution compared with up to four times the image area of film.
Smaller, more convenient camera size compared to film camera.
Improved transition to highlight due to repro method; we’re not passing light through the heavier film densities to record the scan or enlarge the negative.
Greater flexibility in lighting due to a non-characteristic curve film response.
MegaVision Mono capture has some other advantages when compared with other workflows. MegaVision has always believed in capturing a tonality in the file that matches the tonality of the target. We don’t believe, for example, in making a grade 1 neg for a grade 5 paper.
MegaVision’s Photoshoot software allows the shooter the ability to make a “digital emulsion” that matches the reflection densitometer measured density range of any paper or printing press, or the transmission densitometer measured density range of any transmissive target.
Photoshoot capture software allows the shooter to select a paper to shoot for; including 4 printing press targets, 4 portrait ratios, 3 inkjet targets, 2 RA-4 targets, 2 dye sub targets, the world wide web, Dura-Trans, and others.
Choose a target and Photoshoot loads a file contrast, and a light metering that contains the target’s important aimpoints of highlight and shadow.
MegaVision’s Photoshoot software has a unique Color Coded Light Meter that shows the shooter the highest and lowest separable values on the paper.
Yellow- Highest separable value
MegaVision’s Photoshoot software, paper selectable density range, and Color Coded Light Metering add up to more accurate exposures from more accurate lighting, resulting in better and more emotive pictures.
The relevant files are included on this CD, please feel free to inspect the images and draw your own conclusions.