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Weird Gradient Banding Issues When Saved As .jpeg

31 posts in this topic

Posted (edited)

Hi guys, I have been experiencing a weird problem with some of my renders and really need some help if possible. Basically, I am exporting my image as a .tiff file and then importing it into Photoshop, cropping as required and saving out as a .jpeg using highest quality settings. However, when I do so I have noticed some of my images show major problems with gradients and banding as shown in the screen shots below. As far as I am aware I am using RGB colours in Cinema and I just don't know what to do here. Any help would be greatly appreciated.

IMAGE shows a section of the image badly affected when saved to a .jpeg.

post-44915-1248127438_thumb.jpg

Thanks,

vreb

Edited by vreb

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Posted

Try saving it as a 16 bit PSD format and then export it to an 8 bit Jpeg.

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Posted

Wild stab in the dark-

It might be your colour profile in P/shop -try edit, convert to profile, -sRGB & then saving as a jpeg.

Regards

Andy :)

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Posted

Thanks guys, I'll give your suggestions a try and see if that helps.

L8rz,

vreb

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Posted

Well, none of those ideas worked but thanks anyway. I have tried exporting as a .jpeg directly from Cinema too, and get the same issues. I have checked I am using RGB and can't understand it.

Cheers,

vreb

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Posted

Can you post a simple scene file with your render settings and this errant material. A simple sphere and plane should do.

Could you also add a matching snap of the original render which has none of the banding. Just for comparison.

Cheers, Alan.

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Posted

Hi Alan, thanks for the help here. I will provide the info and files you need first thing tomorrow if thats ok as its now 01:09 and my machine is now rendering. I really appreciate the help and will get everything for you as soon as I can. More than anything, this is one of those issues which I really want to know the answer to for both my own sanity and future reference in case I come up against it again. Speak soon and all the best,

vreb

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Posted

I love these little technical puzzlers, they brighten up my day.. I mean night.. or whatever o'clock it is. :)

Cheers, Alan.

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Posted

This is a very common problem when working with Gradients going from 16bit's to 8bits. May I suggest you use a higher bit depth file format than 8 bits?

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Posted (edited)

Hi Guys, thanks for the info.AlanBell, as far as I am aware I am not using any 16-bit files and am exporting 8-bit .tiffs from Cinema too. So I don't think the problem is being caused by converting from 16 bit to 8, but I'll double check that anyway so thanks.

I can't post an image of the problems I am having because as soon as I save the .tiff file as a .jpeg file it causes the issues to appear and I don't think I can post a .tiff file right? I will put these files in a zip.

Alan, I have forgot how to provide the file for you as it is a .zip. I have attached it here but can't remember if there was another way I was supposed to do it. Please could you advise as you need to see the full size .tiff original VS the saved .jpeg to really see the issues.Thanks again for this and I am extremely grateful for any time you may spend on it.

Thanks,

Jay

Files here:

There is an original .tiff file to compare against a saved .jpeg file and one .c4d file too. Please make sure you are viewing through perspective on main camera when you open it. The just render it as a .tiff and saved to a .jpeg to see the issues. You can even just export directly as a .jpeg and you get the same issues too. It has to be a colour problem I am sure but as I am only using 8-bit files I just don't understand how!

Edited by vreb

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Posted

There isnt any difference between the jpeg and the tiff, visually or comparing in Pshop using image calculations. No banding, nothing like that. There is only a maximum 1% difference using calculation, which is probably a result of the jpeg compression.

wilson

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Posted (edited)

Hi Wilson, thanks for the info. Have you looked at my images or are you just talking from experience as I can see huge differences between the two images (.tiff & .jpeg) on my monitor. The gradient areas look very compressed and almost pixelated in some areas on the .jpeg image. I don't understand what I can do about it though as I am saving using the highest quality .jpeg setting too. I would be interested to know if anyone else can see the differences between both the .jpeg and .tiff files too. I have two very high quality HP monitors running in sRGB mode, but doubt they could be any cause of such issues here. I rendered the image out to .tiff, then looked at it at 100%+ and it looked fine. Once saved to .jpeg and viewed at 100%+ you can really see the difference in quality and all the bad artifacting in the .jpeg.

Cheers,

vreb

Edited by vreb

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Posted (edited)

Ok, so I need a sanity check here please guys. I have attached another partial image of another render that was exported from Cinema as a .tiff and then saved down to a .jpeg. I have circled (in black) two problematic areas which appear to also be affected by the same issues here. Please can someone kindly confim that they can also see the area circled. They look like I have used a square brush and dragged it diangonally over the circled area, creating a lighter and pixelated area. I originally posted the image on the site before realising it would take up too much space here, so have added it to a .zip file. However, when I viewed the image on this site I could not see the problem areas quite as easily. I really need someone else to varify they can see it too.

To save space on this site I have added the single .jpeg file (virus scanned) to a .zip file for download.

issueFile.zip

Thanks,

vreb

Edited by vreb

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Posted

Hi Vreb

Yes I compared the images using a calibrated LaCie monitor. I just don't see any of the artefact settings you describe. Either in the two files you supplied earlier or in the new ones where you have circled the problem areas.

Try getting the two images open in Pshop. Then going to Image/Calculations and in difference mode you can compare by channel any difference between the two.

I know this doesn't solve your problem, but the jpegs are fine. I dont know what to suggest could be causing THE VIEWING PROBLEM

WILSON

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Posted

Hi Wilson, thanks for checking for me. So you can see ANY problematic areas at all? Your monitors should be better than mine and the fact your are correctly calibrated really helps too. I am stuck now as surely it can't be my monitor? If it is then why would the .tiff files look perfect and only the .jpeg file show the issues. Surely you would think the problem area would either show or not show on both? Ah, now I am woried it could be my monitors but I ahve had my client also say they could see these areas too? Any further help would be greatly appreciated.

Thanks again,

Jay

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Posted

Hi Jay,

After a first look at your files, I cannot see anything wrong in the text block image within the circled areas. Maybe auto-suggestion makes it 'look like' there is something there.

Colour Sampling does not show any RGB differences where you say there is a stripe.

There IS a more serious banding problem on the back and inner extrusions on the 'C'.

Is the text still a Text/MoGraph object or has it been made editable, ie converted to geometry.

There was a topic just last week about a red material causing issues. This was not a C4D issue but a problem with the colour red itself. Anyone else remember the post?

The vein images only show the expected differences due to jpg compression artifacts.

Stacking them in Photoshop and viewing on a channel by channel basis in Difference mode only shows edge differences.

I'm doing a couple of test renders with the vein scene file to see if anything comes up.

If possible, zip and attach the Finance file.

Cheers, Alan.

BTW, put indicator circles on a separate layer using a stroked 1 pixel marquee selection.

Bold black rings are a visual interference for checking render artifacts.

Alternatively supply a marked thumbnail for reference.

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Posted

Hi Alan, thanks so much for this. I was the person who posted the topic on the red material (colour) issues last week too. I am currently pulling my hair out trying to figure this out. I paid about £300 per monitor but don't have them calibrated really. I have tried using the sRGB calibration profile but it just doesn't look right. I have it on custom profile at the moment, as soon as I select sRGB profile all my colours go really dull and tinted with red, which can't be right? I have selected to use sRGB in my display settings for each monitor, but can't use the profile option from the monitor itself. However, I don't think this is the problem but can't be sure any more. I have tried all profiles are still see the issues I have described and only in a .jpeg image though. The issues with the red colour are there throughout though. I have attached the finance files for you too. All of these show MAJOR anti-aliasing issues when rendering out to Pal or NTSC only. HD is fine.

Thanks again and all the best,

Jay

problemFiles2.zip

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Posted

OK Jay, got the file. I'll be back later with anything I can find.

Cheers, Alan.

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Posted (edited)

Thanks Alan, I really appreciate it. As soon as I get another job I will make another donation to the cafe too, but been unemployed for about 4 weeks now after being made redundant and my only source of income now is selling stock images, which is why this is so important.

All the best,

Jay

Edited by vreb

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Posted

I'm assuming you're working on PC, so I dont know what options you have for calibrating or profiling your monitor, but on a Mac the built in calibrator in system preferences is much better than nothing. It sounds like this is your problem.

Just applying an sRGB or any other profile could give you worse or more inconsistent results than having nothing at all applied. Sorry I cant offer more help - I just dont know how PCs work

WIlson

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Posted

Hi Wilson, yes at first I thought maybe it could be my calibration but then this wouldn't explain the weird patterns of compression and gradient banding I am seeing when viewing .jpegs only. It must be a colour or compression issue but finding out is really hard.

Thanks again though and yes I am using a pc.

Cheers,

Jay

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Posted

Part of the problem is that you are only getting red pixels involved. A jpeg does have the possibility for millions of colors 255 X 255 X 255 = 16,581,375. Unfortunately when you save from tiff to jpg the compression squeezes all those red channel pixels.

To fix your problem I recommened putting a 1% noise filter over your entire image in Photoshop. Do not use monochromatic. You want to introduce blue and green into that red area. Then save as jpg and you will see a big difference. Your gradient shading will be much smoother.

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Posted

Hi baramdo,

Thanks so much for the info here, it is really appreciated and I will go try it now. Can I just check that you can also see problem too please, as so far nobody else has said they can even see the problem and I am going crazy here checking it on both monitors and from diferent angles etc.

Thanks again,

vreb

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Posted

To make you feel a bit better: I can see a little stroke from a certain angle on the text in the .jpeg you posted. If I look straight at my monitor it isn't visible at all.

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Posted

I didn't see anything on the image of the text. On the vein I did notice a flattening of the shadows and highlights. It was small but noticable. You only have 0 - 255 colors of each channel. The compression was just part of the jpg algorythm (sp?). That is why I suggested adding the noise. This adds information to the color channels in the areas that were all red.

My monitor is a Dell 2005FPW. PC based.

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