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K.Spacey - K-PAX
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Image quality

After the different aspects discussed so far, it's time to concentrate on one last aspect, that is "image quality". Now of course this is a broad term, so to make a meaningful comparison between the different films, I set a goal:

"How good do the films and digital shot reproduce all of the details in the original test chart?"

So, if we assume our goal is to reproduce the test chart on it's original size (60 x 90 cm) by printing it based on these scans and digital capture, how much detail will be lost (if any)? So we strive for a 1:1 reproduction here.

Now, to see how well these scans reproduce the original test chart, I show a section of a direct flatbed scan (Canon 9950F) for comparison. This scan was made on a 300 ppi (pixels-per-inch) resolution, and as you can see, it already starts to reveal the test chart's offset screen printing pattern. So this scan represents the maximum quality to be expected from the film scans. All of the images below are again at "actual pixels" (100% viewing) level, so each captured pixel is truly visible. Do note though, that the crops presented here are actually enlargements compared to the 60 x 90 cm test chart because of this "actual pixels" level viewing. To see the scans matched to the exact size of 60 x 90 cm, see the next page.

In the direct scan, I have marked four important details:

1 - hair detail

2 - eyebrow detail

3 - eyelash detail

4 - lip detail

To reveal these details optimally, I have sharpened all of the images compared to the unsharpened scans, as it helps bring out the detail and makes the comparison with the in-camera sharpened Alpha 900 image more fair. All film scans are 4525 ppi, downscaled from the original 8000 ppi scans using bicubic interpolation in Photoshop. Downscaling them to a size similar to the Alpha 900 shot makes the comparison easier, while the fact that were talking about a downscaling of a much bigger scan, means we are not "inventing" new pixels as in an upscaled interpolation from a lower resolution image, but rather emphasizing and using all of the captured detail of the original 8000 ppi scans. Downscaling from such high resolution scans, also helps decreasing the grain and noise pattern a bit.

I have now also included two extra crops for Kodak Ektar 100 and Kodak Portra 160VC. The left images represents the original scan results, the right after color noise reduction, which combats the usual red/green color noise typical and visible in these extreme high resolution color negative scans. No noise reduction was applied to the Fuji Velvia 100 image, as this scan already had a low color noise level. If you are not familiar with digital image processing, you may wish to skip the next paragraph and just go on to view the images, as it may be a bit to cryptical.

Color noise reduction was achieved by converting the images to LAB color mode, and than applying a mild Gaussian blur with a radius of 5 pixels to the A and B color channels, after which both of these channels were sharpened up again to prevent color bleeding. The advantage of this method of color noise reduction is that it hardly affects image detail, as that is for the most part contained in the untreated L or Lightness channel of LAB color mode. It is about similar to what Photoshop's "reduce noise" filter does when set to remove color noise only. Overall sharpening was achieved by sharpening up the L or Lightness channel. The effect of the color noise reduction is especially visible in the grey background. I may go deeper into this subject of color noise and noise reduction in a later technical article.

Direct flatbed scan of test chart (Canon 9950F)

Kodak TMax 100

Canon 9950F direct scan Kodak Ektar 100

 

Kodak Portra 160VC

Kodak Portra 160VC - NOISE REDUCTION

Canon 9950F direct scan Kodak Ektar 100

 

Kodak Ektar 100

Kodak Ektar 100 - NOISE REDUCTION

Canon 9950F direct scan Kodak Ektar 100

 

Fuji Velvia 100

Sony Alpha 900

Fuji Velvia 100 Sony Alpha 900

Now looking at the direct scan and comparing the different images with it:

Kodak TMax 100:

Loss of detail in hair (1) compared to direct scan. Just very faint detail in eyebrows and eyelashes (2 and 3). Lips reveal some of the highlight detail.

Kodak Portra 160VC:

Loss of detail in hair (1) compared to direct scan. However, light thin hair details better defined than in TMax 100. Just very faint detail in eyebrows and eyelashes (2 and 3). Lips reveal some of the highlight detail. Slightly less grainy than TMax 100, but more grainy than Ektar 100.

Kodak Ektar 100:

Some loss of detail in hair (1) compared to direct scan. Just very faint detail in eyebrows and eyelashes (2 and 3). Lips reveal some of the highlight detail. Actually, despite the visibly finer grain, difficult to distinguish in terms of detail compared to Portra. I still wonder if I got the focus 100% right?

Fuji Velvia 100:

Some loss of detail in hair (1), however overall better rendition of hair detail. Of all films most visible detail in eyebrows and eyelashes (2 and 3), better separation of eyelashes. Lips clearly reveal some of the highlight detail (4), even the two most right situated highlights are separated.

Overall, the differences are now smaller than before with the new scans. Especially the color negative films, despite showing a more visible grain, have benefited.

Sony Alpha 900:

Some loss of detail in hair (1), however the least. Visible detail in eyebrows and eyelashes are (2 and 3). Lips clearly reveal some of the highlight detail (4), even the two most right situated highlights are separated. Best detail overall, very fine rendition of hair.

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