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04-02-2014, 01:30 PM   #16
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I did a search through Google and found a lot of people complaining about the same problem as far back as 2005 with Pentax dslr cameras both in this forum and Dp review. A number of the respondents took a raw photo supplied by the originator of the complaint and opened it in Lightroom and could see no banding. However, When opened in a free converter such as Faststone, (the one I used) the banding was apparent. It was deduced that Faststone default settings dealt only with a reduced quality digital capture that showed banding and the way to deal with this was to set the default capture setting in Faststone to ' View in actual size - slower,' and batch convert in actual size - slower'. I did this and the banding did not appear in photos where I had previously seen it. So, if we get any more blue sky this year I will test out my theory and report back.

I would agree it is not the lens, nor do I think it's the camera, I am new to Pentax and I think it's my inability to grasp the rules behind RAW capture and conversion. It appears, in order to speed things up Faststone abstracts a low quality photo to work on.

As an aside, others mentioned that when converting into jpeg in Faststone file sizes were remarkably small, around 2-3mb. I found that by going into the Jpeg setting tag and disabling colour sub-sampling the same jpegs when converted had file sizes around 24MB. Thank you all for your help

04-02-2014, 01:56 PM   #17
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QuoteOriginally posted by Dartmoorman Quote
It was deduced that Faststone default settings dealt only with a reduced quality digital capture that showed banding and the way to deal with this was to set the default capture setting in Faststone to ' View in actual size - slower,' and batch convert in actual size - slower'.
I believe the default in Faststone is to show the jpeg thumbnail embedded in the RAW. I am not sure if camera jpeg settings affect the embedded jpeg but at any rate you are not looking at a RAW, just the low res thumbnail. As you noted when you actually process the file, Faststone cooks a new jpeg with better results. You might look at your camera jpeg settings and test if they have any affect on the resulting RAW embedded thumbnail.
04-02-2014, 02:27 PM   #18
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I have looked at this image multiple times and it simply does not look like typical 8-bit reduction banding. My first thought was a flaky polarizer filter. After thinking on it a bit, I suspect that it has to do with JPEG compression, resizing after JPEG creation, or something more involved. The banding in the photo is an interference pattern, not the usual step-wise discontinuity.

Tell me, is it normal for Fastone to render to 8-bit TIFF before converting to JPEG? The IPTC has a trail that sort of looks that way.

Any chance of dropping the DNG file anywhere for download?


Steve

---------- Post added 04-02-14 at 02:30 PM ----------

QuoteOriginally posted by Dartmoorman Quote
I did a search through Google and found a lot of people complaining about the same problem as far back as 2005 with Pentax dslr cameras both in this forum and Dp review.
I remember several from way back as well, but most were traceable to wide expanses of blue sky with a polarizer in the mix.


Steve
04-02-2014, 03:20 PM   #19
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QuoteOriginally posted by twitch Quote
Any image on screen is a jpeg conversion of your RAW file
Can't see why not, Twitch.

Software surely decides between displaying the RAW image, any jpeg preview from the camera contained in the file, or its own rendering.

04-02-2014, 03:33 PM   #20
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QuoteOriginally posted by clackers Quote
Can't see why not, Twitch.

Software surely decides between displaying the RAW image, any jpeg preview from the camera contained in the file, or its own rendering.
There is no "RAW image", only the software's rendering/interpretation of the image from the RAW data. If you're looking at it and it's not a bunch of 1's and 0's, it's been rendered by something- your converter or your camera (as with the embedded preview).
04-02-2014, 03:47 PM   #21
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QuoteOriginally posted by twitch Quote
Any image on screen is a jpeg conversion of your RAW file.
Not really. The image on the screen is a bit-mapped raster interpretation of the data stored in the original file. This is true regardless of format with the possible exception of the native bit-map format supported by the OS (e.g. Windows .bmp). When a RAW converter such as Lightroom (essentially Adobe Camera RAW) displays a RAW file, it does a temporary interpretation of the capture data into the graphics memory based on default development settings. When your browser displays a JPEG image, the contents are also rendered into the graphics memory, but in a manner specific to the JPEG format with all information required for display encoded in the file itself.

For Pentax the RAW rendering is (or should be) either a full 14-bit or 12-bit image depending on camera. JPEG is always 8-bit (256 color shades maximum per channel R/G/B) regardless of the color depth of the original capture. An interpretation of the RAW data into JPEG almost always involves a munging of color values to fit the 8-bit limitation with significant opportunities for artifact and/or color shift. This can be demonstrated by doing a screen capture of both the displayed RAW data and that from an exported JPEG of the same image. A comparison of full-resolution crops from both is usually quite telling. They are not the same.

You are correct, however in laying the blame on the RAW converter if it does intermediate processing that results in display artifact. I suspect this is what is being done by Fastone. That is why I suggested making the DNG available for download so we could take a look-see at the unprocessed file in the RAW converter of choice.

As for color space conversion issues, I don't know that it would cause the problems present in the original post. Conventional wisdom is to capture and edit using a wide gamut and eventually down-sample to sRGB if screen display is the target to allow for consistent display across devices.


Steve

Last edited by stevebrot; 04-02-2014 at 03:57 PM.
04-02-2014, 04:10 PM   #22
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QuoteOriginally posted by BrianR Quote
There is no "RAW image", only the software's rendering/interpretation of the image from the RAW data. If you're looking at it and it's not a bunch of 1's and 0's, it's been rendered by something- your converter or your camera (as with the embedded preview).
Of course there is.

You can say the same thing about the TIFF, Jpeg or GIF formats.

A bunch of zeroes and ones that the software renders.

The only difference with a RAW file is that the camera hasn't imposed itself on the sensor data first (which does happen, eg Sony compression).
04-02-2014, 05:31 PM - 1 Like   #23
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QuoteOriginally posted by clackers Quote
Of course there is.

You can say the same thing about the TIFF, Jpeg or GIF formats.

A bunch of zeroes and ones that the software renders.

The only difference with a RAW file is that the camera hasn't imposed itself on the sensor data first (which does happen, eg Sony compression).
Not quite, but close. RAW output has gone through the camera's image processor engine (not the same as the JPEG engine), but has not been rendered to any of the commonly available standard image formats used for photographs.* What's more it completely lacks the information to do so short of a few hints regarding white balance and such. A TIFF or JPEG file, on the other hand, has all the information required for rendering built into the file. RAW output truly is a type of digital negative that requires significant input** and processing before a usable image can be rendered to memory and even more processing before that rendering can be output to an image file that may be viewed on a different device.


Steve

* JPEG, TIFF, PNG, and so on. DNG is based on the TIFF/EF standard, but this is not the same as the Tagged Image File Format (TIFF) for lossless full-information images.
** It is not well-appreciated that all RAW converters, including the in-camera JPEG engine, apply a set of "development" parameters to the RAW output that allow it to be viewable. A good example would be an import into Lightroom where a default profile is applied to the data to allow rendering to the graphic memory.


Last edited by stevebrot; 04-02-2014 at 05:39 PM.
04-02-2014, 06:39 PM   #24
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*** Please disregard this ***


Does nobody else have a issue with the OP's workflow, you all seem to approve of it.


He takes the 15mb raw file and then instead of post processing it, he generates an output file, but not the 48mb TIFF it offers, that is way too large, so he downsamples it and turns it into a 4 mb TIFF but he is unhappy that this is so big so he generates a tiny Jpeg.


Then when he has this tiny Jpeg as a source file he begins to post process the image and notices banding and artefacts.


Did I misunderstand something?


I have suggested he preserves his image file sizes without downsampling and compressing them until right at the end of the workflow, and post process the images without downsampling or compressing them, but I had my hand slapped for suggesting such a thing.


I have never heard it suggested before that its a good idea to downsample a TIFF from 49mb to 4mb, and then after that to apply a Jpeg lossy compression, and then after that to begin post processing the resulting image.


Is nobody going to put him straight on this or am I the one with no idea how to post process an image. Am I being an idiot here and your all using this kind of workflow. Id like to know because im stupidly post processing the original files my camera produces, and im handling files files 20 times bigger than his during post processing.


Lets say you solve this issue, isn't his workflow going to cause other banding issues so hes no better off anyway and he'll be back asking for a solution to those new issues, or do I know nothing here.


I feel now that I obviously know nothing about post processing, why don't the camera manufacturers sort this file bloat out, and make the cameras create 1 mb raws, and 4 megabyte TIFFS if that's all we really need.


I certainly feel that his downsizing and compression is acceptable to all of you and you must all be producing good work from 4 megabyte TIFFS or 100kb Jpegs.


When I downsize and compress images like he is doing I suffer banding and artefacts. Clearly im the one at fault here and im clueless.


Is it the software im using, I thought photoshop was supposed to be good, help me out.


What am I doing wrong here guys, should I adopt his workflow, downsample every image as a first step and do all my post processing and production work on 100kb Jpegs, please enlighten me.


****************************************************************************************************************************************


Please disregard this post, I cannot find the post I thought I was referring to.


Apologies to the OP and the other members I may have mislead.


I will leave this post in situe as other posts refer to it.


Im eating humble pie now.

Last edited by Imageman; 04-02-2014 at 10:27 PM. Reason: the post was clearly wrong
04-02-2014, 09:55 PM   #25
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QuoteOriginally posted by Imageman Quote
I certainly feel that his downsizing and compression is acceptable to all of you and you must all be producing good work from 4 megabyte TIFFS or 100kb Jpegs.
I have been trying to figure out the workflow myself because I too suspect it to be the problem. Did I miss a post somewhere or are their some elements in the metadata that I am not able to interpret? I don't remember anyone talking about converting from RAW to downsized TIFF and from downsized TIFF to JPEG. Downsizing like that could create a pattern such as in the image in the original post.


Steve
04-02-2014, 10:10 PM   #26
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QuoteOriginally posted by stevebrot Quote
I have been trying to figure out the workflow myself because I too suspect it to be the problem. Did I miss a post somewhere or are their some elements in the metadata that I am not able to interpret? I don't remember anyone talking about converting from RAW to downsized TIFF and from downsized TIFF to JPEG. Downsizing like that could create a pattern such as in the image in the original post.


Steve
I was wondering about this myself, having seen a similar thread, which I believe is this one: https://www.pentaxforums.com/forums/32-digital-processing-software-printing/2...mpression.html Similar problem from a different OP.
04-02-2014, 10:12 PM   #27
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QuoteOriginally posted by stevebrot Quote
I don't remember anyone talking about converting from RAW to downsized TIFF and from downsized TIFF to JPEG.
Oh...now I think I see it.

Code:
<?xpacket begin='' id='W5M0MpCehiHzreSzNTczkc9d'?>
<x:xmpmeta xmlns:x='adobe:ns:meta/' x:xmptk='Image::ExifTool 9.54'>
<rdf:RDF xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
<rdf:Description rdf:about='' xmlns:exif='http://ns.adobe.com/exif/1.0/'>
<exif:CompressedBitsPerPixel>0/1</exif:CompressedBitsPerPixel>
<exif:Flash rdf:parseType='Resource'>
<exif:Fired>False</exif:Fired>
<exif:Function>False</exif:Function>
<exif:Mode>2</exif:Mode>
<exif:RedEyeMode>False</exif:RedEyeMode>
<exif:Return>0</exif:Return>
</exif:Flash>
</rdf:Description>

<rdf:Description rdf:about='' xmlns:tiff='http://ns.adobe.com/tiff/1.0/'>
<tiff:BitsPerSample>
<rdf:Seq>
<rdf:li>8</rdf:li>
</rdf:Seq>
</tiff:BitsPerSample>
<tiff:ImageLength>3264</tiff:ImageLength
<tiff:ImageWidth>4928</tiff:ImageWidth>
<tiff:YCbCrCoefficients>
<rdf:Seq>
<rdf:li>0/1</rdf:li>
<rdf:li>0/1</rdf:li>
<rdf:li>0/1</rdf:li>
</rdf:Seq>
</tiff:YCbCrCoefficients>
<tiff:YCbCrPositioning>0</tiff:YCbCrPositioning>
<tiff:YCbCrSubSampling>
<rdf:Seq>
<rdf:li>1</rdf:li>
<rdf:li>1</rdf:li>
</rdf:Seq>
</tiff:YCbCrSubSampling>
</rdf:Description>
</rdf:RDF>
</x:xmpmeta>
The XMP indicates a 16 megapixel 8-bit TIFF at some point.


Steve
04-02-2014, 10:22 PM   #28
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Apologies to the OP for my earlier post, I will amend it.


I cannot find the post I responded to. Please ignore it and accept my apologies
04-02-2014, 10:27 PM   #29
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QuoteOriginally posted by Imageman Quote
Apologies to the OP for my earlier post, I will amend it.


I cannot find the post I responded to. Please ignore it and accept my apologies
Ummm...do cross-out so as to not make the rest of us look like fools.


Steve

---------- Post added 04-02-14 at 10:30 PM ----------

QuoteOriginally posted by Imageman Quote
Im eating humble pie now.
No problem. Right forest, wrong tree. I suspect you are on to something, but also suspect that the OP has gone on to other tasks. We may never know.


Steve
04-02-2014, 10:35 PM   #30
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Thank you Paulh, you resolved this.


I stupidly got mixed up and turned around and posted in the wrong thread.


Once again my profound apologies to the OP Dartmoorman and the members who read my bad post.
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