X-10 canvas-like texture in dark areas

Started Dec 31, 2011 | Discussions
PabloF
PabloF Senior Member • Posts: 1,047
X-10 canvas-like texture in dark areas

Hi everyone, this is my first post here, although I've been posting on the Pentax SLR forum for some years. In need for a take-anywhere/travel camera I had been reading this forum for some time looking at the Fuji X-10, which appealed to me particularly for the viewfinder, manual zoom, bright lens, raw capability, and compact size. I also had good memories of my first digital camera, a FujiFilm MX-1700Z, which served me very well. However I was a bit put off by the orbs, and the "quirks" reported by some, so I was still undecided when... my wife got me one for Christmas!

So I've been using it for a few days and it is indeed a little quirky, but it's a great little camera, I'm getting to know it better everyday and I think I'm going to be taking it almost everywhere!

I do have a concern however. When shooting jpg L the photos display a peculiar canvas-like texture in the darker areas. Here is an example to illustrate my point:
Full image, resized:

100% crop 1 - look at the blue leg chair and area to the left:

100% crop 2 - see the wall behind the candle:

Has anyone seen anything similar? I haven't seen this on any images posted here or in the DPR samples. Any feedback would be highly appreciated. Thanks in anticipation!
--
Paolo
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Trevor G Veteran Member • Posts: 6,577
Re: X-10 canvas-like texture in dark areas

PabloF wrote:

I do have a concern however. When shooting jpg L the photos display a peculiar canvas-like texture in the darker areas. Here is an example to illustrate my point:

Has anyone seen anything similar? I haven't seen this on any images posted here or in the DPR samples. Any feedback would be highly appreciated. Thanks in anticipation!

I cannot answer the texture issue (it looks a lot like noise) except to say that, in my testing, L size is not much of any sort of advantage at all. It is fuzzy and indistinct (although it will sharpen up OK) and when compared with an M size image of the same scene, M is sharper, clearer and...better.

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Cheers

Trevor G

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Trevor G Veteran Member • Posts: 6,577
Re: X-10 canvas-like texture in dark areas

Can I also suggest that you use M with DR400 to save your highlights?

Your images look great, but they show signs of clipping.

The X10 has an amazing highlight recovery ability in RAW of very close to 3EV. That's 2EV more than my 6MP Pentax *ist DS2 DSLR.

I found that by using DR400 and then using the RAWs that I seldom need any -ve EV compensation.

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Cheers

Trevor G

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PabloF
OP PabloF Senior Member • Posts: 1,047
Re: X-10 canvas-like texture in dark areas

Thanks for the suggestions. I will try your suggested settings. It strikes me however that with the default factory settings you shouldn't expect this level of artifacts. A defective specimen?

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Peter Rowe Contributing Member • Posts: 593
Re: X-10 canvas-like texture in dark areas

This looks to be artifacts from the demosaicing process where missing colors are interpolated from surrounding pixels. It usually occurs when there is strong sharpening (if you grossly oversharpen any image you will see it). Try a less-strong sharpening setting and see if the effect is reduced or goes away. As it is it will probably never show up in print or be noticed at display sizes. It's a normal part of the digital work-flow process so nothing is likely broken.

Good luck with your new camera, the X10 is a really great piece of equipment.

Tom Schum
Tom Schum Veteran Member • Posts: 7,771
Re: X-10 canvas-like texture in dark areas

Yes, I saw that in one of my shots. And, I was shooting full size (12mpx, 4000x3000).
It was in program mode ("P" I believe), with noise suppression set to minimum.

It is a look like woven cloth. Maybe it has something to do with the EXR sensor, the two halves trying to interleave and so on.

Here is a 100% crop from a background area in that shot. Is this what you mean?

I've been shooting in EXR mode and mostly in medium size jpg since then, and have not seen it (or at least, I have not found it bothersome). Even this is not that big a deal for me. I guess I am too easy to please, but I have a DSLR for the demanding image quality stuff and an X10 for the fun stuff (basically all I do these days).

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Tom Schum

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PabloF
OP PabloF Senior Member • Posts: 1,047
Re: X-10 canvas-like texture in dark areas

Yes, that looks like the same artifact. I can see it in most of my images shot in L size and P mode. It doesn't appear when shooting EXR (hence M size). I will try M size in P mode and see if it still appears.
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Paolo
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PabloF
OP PabloF Senior Member • Posts: 1,047
Re: X-10 canvas-like texture in dark areas

Thanks. The sharpening is set to the factory default, which I believe is not particularly strong. But I'll try reducing it and see what happens.
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Paolo
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Kevin Coppalotti Veteran Member • Posts: 9,274
Re: X-10 canvas-like texture in dark areas

The pattern looks like classic EXR artifacts, I've seen similar in the S200exr
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Peter Rowe Contributing Member • Posts: 593
Re: X-10 canvas-like texture in dark areas
edu T Senior Member • Posts: 1,174
Re: X-10 canvas-like texture in dark areas

Tom Schum wrote:

Yes, I saw that in one of my shots. And, I was shooting full size (12mpx, 4000x3000).
It was in program mode ("P" I believe), with noise suppression set to minimum.

It is a look like woven cloth. Maybe it has something to do with the EXR sensor, the two halves trying to interleave and so on. (...)

...with one half failing to blend into as it looks like --throughout the image, not only in darker areas-- for every normally rendered pixel there is a missing one being chroma-interpolated after its loss?

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max metz Senior Member • Posts: 2,644
Re: X-10 canvas-like texture in dark areas

Congratulation on your new camera Paolo, judging by the light control and excellent composition in your frame, another x10 has found a very deserving home. I love mine!

The artefact you describe is certainly there, I hadn’t noticed it before but I don’t use P mode only Aperture or Shutter priority in PASM, I wonder if it is also in the EXR HR mode – I’ll have to have a look as I haven’t tried that mode yet. It does look like a sharpening or local contrast artefact but I am only guessing.

For me at least, the 12mp method in this camera still seems somewhat of an enigma, this could be another clue.

Kindest regards to you and happy new year.

drummerman Regular Member • Posts: 297
6mp only?

Are most of you saying that 6mp is really optimal??

regards

Paul De Bra
Paul De Bra Forum Pro • Posts: 12,541
Yes, that's been stated many times: 6MP.

The 12MP are mostly there for marketing. The X10 has 12 million pixels but it is not a 12MP camera. A 12MP camera with 4:3 aspect ratio would have a sensor of 4000x3000 pixels. The X10 does not (nor other EXR models). The X10 has 2 arrays of just over 2800x2100 and they are offset diagonally. So the camera has to create an image out of these 2 arrays. Note that this corresponds to a 5600x4200 array of which only half of the elements have any light. So to produce a 12MP image the camera has to do quite a bit of processing to obtain a 4000x3000 rectangular picture.

Obtaining a 2800x2100 picture is easy though as it's just a matter of combining the 2 arrays in the right way (binning pixels for SN mode or exposing them differently for DR mode).

So for all intents and purposes the X10 really is a 6MP camera although it has a 12 million pixel sensor.

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PabloF
OP PabloF Senior Member • Posts: 1,047
Re: Yes, that's been stated many times: 6MP.

Paul De Bra wrote:

Re: Yes, that's been stated many times: 6MP.

The 12MP are mostly there for marketing. The X10 has 12 million pixels but it is not a 12MP camera. A 12MP camera with 4:3 aspect ratio would have a sensor of 4000x3000 pixels. The X10 does not (nor other EXR models). The X10 has 2 arrays of just over 2800x2100 and they are offset diagonally. So the camera has to create an image out of these 2 arrays. Note that this corresponds to a 5600x4200 array of which only half of the elements have any light. So to produce a 12MP image the camera has to do quite a bit of processing to obtain a 4000x3000 rectangular picture.

Obtaining a 2800x2100 picture is easy though as it's just a matter of combining the 2 arrays in the right way (binning pixels for SN mode or exposing them differently for DR mode).

So for all intents and purposes the X10 really is a 6MP camera although it has a 12 million pixel sensor.

Thanks for the explanation. I had not come across such statements before. I'm not a Mpixel freak and I'm quite happy with 6MP as "standard" resolution if that means good IQ and the declared advantages of EXR.
However, looking at the link provided by peter Rowe above:
http://www.pages.drexel.edu/.../40D_Demosaicing/40D_DemosaicingArtifacts.html

the artifact I am referring to looks very much like an incorrect demosaicing being applied by the in-camera jpg engine. I will be trying some RAW shooting and conversions with different SW, and it will also be interesting to see the DPReview tests
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drummerman Regular Member • Posts: 297
Re: Yes, that's been stated many times: 6MP.

Wow. Thank you.

Whilst I appreciate that MP are not the most important factor, at this day and age 6mp seems rather tight, especially if larger prints are needed though I appreciate that many of you just use the X10 as a P&S and have larger cameras for more important work. So I guess it fullfills its promise as made by Fuji ...

regards

PabloF
OP PabloF Senior Member • Posts: 1,047
Re: X-10 canvas-like texture in dark areas

Peter Rowe wrote:

It is demosaicing:

http://www.pages.drexel.edu/~par24/rawhistogram/40D_Demosaicing/40D_DemosaicingArtifacts.html

Thank you Peter, it looks as if you've nailed it. I will try some out of camera RAW conversions to see if the artifacts persist
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Paolo
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PabloF
OP PabloF Senior Member • Posts: 1,047
Re: X-10 canvas-like texture in dark areas

I have done a quick test: the same scene was shot in
a) L jpg;
b) L RAW and converted in Lightroom 3.6;
c) M jpg;
d) M RAW and converted in LR 3.6

Whole image a), resized:

100% crop of a):

100% crop of b):

100% crop of c):

100% crop of d):

All photos in P mode, DR 400;
a) and b) at ISO 400, c) and d) at ISO 100

Quick conclusion:

the demosaicing artefact (if that's what it is) is visible in a) only (look at the bush near the center of the image, between the 2 trees);

the Lightroom raw conversion eliminates the artefact, but the image is quite noisy.

Images taken in M size do not display the demosaicing artefact, whether in camera jpg or recorded raw and converted in LR.

I have repeated the above sequence on 2 other sets of photos, with the same results.
Anyone else with the same experience?
Happy New Year to all

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Tom Schum
Tom Schum Veteran Member • Posts: 7,771
Re: X-10 canvas-like texture even in EXR mode!

I did a test this evening using a bright light to illuminate a nice pottery piece, one of my wife's favorites.

I get the canvas-like texture on every combination of 12 Mpix shots that I tried, and all EXR shots.
I do not get it when I use 6 Mpix mode: Size M, quality F, ISO 100, DR100.

I used JPGs right out of the camera and post processed them in Photoshop Elements 9. The EXR shot was sharpened 100% at a radius of 0.3 pixels, and the 6 Mpix shot was sharpened 400% at a radius of 0.3 pixels, because I was unable to see any texture at any level of oversharpening. The 12 Mpix shot was not sharpened. On all these shots I used Photoshop to brighten the cropped areas as well. All the 100% crops view the same area in the top right of the image. All shots were done with -1 EV (didn't notice this at the time).

On the 12 Mpix 100% crop, I tried downsizing by the root of 2 to give me a view as if it were shot at 6 Mpix, but the texture remained in the downsized image (not shown below).

Going into this test, I expected to find that this problem was related to the DR mode setting with large file size only, and would disappear with DR100. Not so!

This problem is easiest to find in slightly unfocused areas that are consistently colored. Look in the green area near the center of the 100% crops, and you will see the texture.

It appears that if I am going to enlarge a photo to the max, I am limited to 6 Mpix mode. The other modes all produce the canvas-like effect, at least on my particular X10.

You might be saying that if I don't oversharpen this will not be a problem. However, after printing a different photo last night (shot with bright lighting at 12 Mpix, then printed onto 13"x19" with Epson R2000) I clearly saw the texture in the print! It's not altogether a bad thing, to have that texture, but it is not very pleasant to have no control of it. That's why I did these tests this evening.

See photos below.

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Tom Schum

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PabloF
OP PabloF Senior Member • Posts: 1,047
Re: X-10 canvas-like texture even in EXR mode!

Tom, thanks for doing these tests and posting the results.

Since my last post I have meant to do some systematic tests to better understand the problem but I only did a few and then I just started using the camera in M mode to avoid it. Occasionally I take some shots in L size and the texture is always there.

The following are a series of images shot in jpg F, L size, Program mode, at 100, 200, 400, 800 and 1600 iso. The 100% crops have some USM sharpening to highlight the texture issue, which however is perfectly visible, when present, on OOC jpgs.

What I see is that the texture appears at 200 iso, is strong at 400 and 800 iso, and disappears at 1600 iso, giving way to a more conventional luminance noise. The texture noise is best visible in the purple area in the centre of the images.
Comments welcome!

100 iso, full image:

100 iso, 100% crop near the centre:

200 iso:

400 iso:

800 iso:

1600 iso:

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