Ugly grid pattern on my slide film scans

TheDarkroom.com uploaded my batch of enhanced scans today. I checked them out, and like 90% set of just my Ektachrome scans have this grid pattern all over the image. I have a set of Ultramax 400 and Ektar 100 enchanced scans from the same order that are totally fine. What in god's name happened to my Ektachrome?

 

Ask Darkroom.

That’s a... something... that happened in the scanner to jpg pipeline. Talk with them about it. They might have to rerun the scanning.

Ask Darkroom.

They said it could happen because of underexposed photos OR something in the scanning process. The roll has images that are average and overexposed. None are so underexposed that they are completely washed out but the grid pattern still appears in the darker areas of the photos. I know it's slide film film with very little latitude and there's always a battle between exposing for highlights or shadows, but this is just ridiculous.

 

I have other shots of the same plant where the petals are completely white and overexposed yet the shadows still have the grid. I've also had enhanced scans done on other slide film's and haven't seen this.

 

 

That’s a... something... that happened in the scanner to jpg pipeline. Talk with them about it. They might have to rerun the scanning.

 

I think you're right. They said it could be from underexposure or the scanning, but check out the other images I posted. I don't think that's underexposure unless the scanner thinks every dark area is underexposed.

I don't know that I have seen it in scans, unless at the lowest (most compressed) JPEG format,

but it appears pretty often in digital video.

 

When the scene changes very fast in video, a lot of change has to compress into

a small number of bits. The one I remember most, is when many flash cameras are going

off at almost the same time.

 

How big are the files, in bytes and in pixels?

Are the slides glass mounted?

Looks like the mottle got from scanning through 'anti-Newton' glass mounts.

Are the slides glass mounted?

Looks like the mottle got from scanning through 'anti-Newton' glass mounts.

 

Yes, I did order mounting.

I don't know that I have seen it in scans, unless at the lowest (most compressed) JPEG format,

but it appears pretty often in digital video.

 

When the scene changes very fast in video, a lot of change has to compress into

a small number of bits. The one I remember most, is when many flash cameras are going

off at almost the same time.

 

How big are the files, in bytes and in pixels?

 

They are roughly 4-5 MB at 3089x2048

This is what they look like close up. They look like scanning "steps" to me. They cover the whole image, just more easily seen in the darker parts

 

It could be the scanner, the mounting of the slides, or the compression. Ask the lab to re-scan to an uncompressed format for a start (.tif). If that doesn't help, and the film has not been in a glass holder, then it's the scanner. Or... get a very good loupe and a bright backlight and check the slides themselves. Maybe it's the film processing?

The grid reminds me of the examples someone posted several months ago where a cell phone was used (experimentally) as a backlight for copying slides.

 

My first attempt at copying with a dSLR

Moiré; a pattern on the film that can interfere with the scanner sensor.

One set is from scanning negative film; the other is from scanning transparency film, and I suspect they are not making the specific adjustments to the scanner for each different film type requiring a change in settings.

 

Also ensure that Ektachrome is not frozen before use, and if refrigerated, it is allowed to reach room temperature over a few hours.

Ah, right. I was looking at the excessive grainy patterning.

 

The grid-like pattern is almost certainly a moiré effect of some sort. I'm still inclined to blame scanning through etched cover glass, but why this would have a regular pattern to cause moiré, I can't fathom. Unless the glass is repeat printed with a coating, rather than randomly etched.

I suspect they are not making the specific adjustments to the scanner for each different film type requiring a change in settings.

It would be a very unusual scanner that introduced moiré patterning with a change from positive to negative film. The inversion and colour correction for negative film is always applied in software. There's no hardware change in the scanner, except for maybe a change in exposure.

This is the full image but the pattern is more pronounced. All I did was resize the OP's pic from 3089 x 2048 to 1000 x 663. This pattern reminds me of troubles I had when I was learning about scanning years ago. From memory, I got patterns when I set several different adjustments and filters like sharpening, grain reduction etc expecting the scanner and software to be able to cope, doing it all in one scan. Obviously it couldn't. Since then I've bought more expensive scanners and software and rarely anything goes wrong.