Rendering Resolution

[glorybound]

This might be a dumb question, but here it goes. I want to render, for the web (1920 x 1080), so do I render at 1920 x 1080? I can get really nice render times, but I am not getting a nice clean image. Or, do I double the dimensions and downsize the image? I can do my own tests, but a quick post is a lot easier.

[Lupaz]

I ain't no expert, but I'll give my opinion.

It depends. What do you mean by clean image? noise? moire?

[glorybound]

Just fuzzy. I see some nice crisp renders on-line, but I am not seeing that in mine

I ain't no expert, but I'll give my opinion.

It depends. What do you mean by clean image? noise? moire?

[Mokiki]

You mean AA problems? If so yes I notice that too. There are some angles were the stepping is really hard to get rid of even with high AA settings + image filter so most of the time instead of cranking up the AA settings I render at 2,7-3k and downsize it to HD afterwards.

[Shimakaze]

What you are talking about is "Supersampling". It's a valid method of anti aliasing, and is used a lot in both realtime and prerendered images. When you use that in vray you effectively antialias the image twice. Not the most effective, but it does work, and is easy to set up. If you find normal images to be too blurry, remember that Vray also applies an antialiasing filter. The regular one, Area, tends to be quite blurry, so you might want to try Catmull-Rom or something similar and see if you like that result better. It might result in moire effects in repeating patterns though.

[Vizioen]

This might be a dumb question, but here it goes. I want to render, for the web (1920 x 1080), so do I render at 1920 x 1080? I can get really nice render times, but I am not getting a nice clean image. Or, do I double the dimensions and downsize the image? I can do my own tests, but a quick post is a lot easier.

Whatever the output I tend to render at 4K; and downsize if necessary. That way I can keep my settings pretty low. But have a nice quality overall.

[Lupaz]

Whatever the output I tend to render at 4K; and downsize if necessary. That way I can keep my settings pretty low. But have a nice quality overall.

I understand doing that with AA problems. But what about a material with gloss in, say, 0.6? even if you render that bigger and then downsize, the noise that you get (with low settings) doesn't just disappear. no?

[Vizioen]

I understand doing that with AA problems. But what about a material with gloss in, say, 0.6? even if you render that bigger and then downsize, the noise that you get (with low settings) doesn't just disappear. no?

Indeed, so I bump subdivs up just enough so it's less noticeable. But in all honesty since taking Grant Warwick's course I'm taking on a different road and balance my settings a bit better to have as little noise as possible. but a 1920 x 1080 resolution for me is always too small, I like to zoom in on details

[glorybound]

Okay, this helps. Thanks!

[joconnell]

A lot of it is what format you're saving in for the web too - the colour quality of a normal render is going to be far higher than a jpeg will for example. Compression can also trash edge detail!

[glorybound]

either a jpg or a gif. What you recommend?

A lot of it is what format you're saving in for the web too - the colour quality of a normal render is going to be far higher than a jpeg will for example. Compression can also trash edge detail!

[joconnell]

For anything with any kind of gradients of colour in it, whether falloff of light, gradients of shies or whatever, then a jpg. Gif can only have a max of 256 colours and if they run out of colours they try to use a pattern of a few different colours to try and fake other colours, similar to how a printer only has four colours but changes it's pattern to give the perception of other colours. Gifs have great compression for things that have blocks or stripes of pixels with the exact same colour so if you're doing graphics such as logos or other quite crisp line art, gifs will look nice and sharp and be small in size. Jpegs can use far more colours so they can keep photographic detail so you'll mainly be using those for your renders. You might have to fiddle with the quality slider of whatever program you're using to make them to get the best balance of image quality versus file size.

[Shimakaze]

I wouldn't worry too much about color for web. The only real issue is going from a floating point HDR file to an 8 bit LDR file. If you render to EXR and open it in Photoshop you will have to convert it down to 8bit at some point, and when you do you have to tonemap it or just cut off excess info. Once you have it down to an 8-bit file what joconnell said is true. JPEG is good for detailed photoesque pictures, but bad at pure color surfaces and line art. Unless you're doing webdesign you're probably gonna use that. If you need vector art to look good, or need in-page transparency, then you have to use another format. GIF is good for simple pictures and silly animations, but it's very limited. PNG has all the advantages of GIF but has much higher image quality (more colors), but might take more space. It's possible to get that size down by using PNGcrush through simple optimization. also, PNG is a lossless format, so you retain the original image quality. JPEG is very lossy, and you have to make sure you set it to a good enough quality for it to look good. (in Photoshop this is easy to do by using the "save for web" feature, which lets you see what it will end up like) GIF is only lossless as long as the original picture contains less than 256 colors, which means almost never except in black and white pictures. Converting to that will mean you have to discard a lot of colors, which may introduce banding and severely limit the dynamic of the picture.


So my advice (if using Photoshop) is to render to EXR (or vrimg), edit as much as you can in 32bit depth in PS, (there are some things you can't do in 32 bit sadly), and then down-convert it to 16 bit/channel.
When you do, if you are already happy with how the image looks, set the tone mapping method to exposure and gamma and fiddle with the settings if you like. (I almost always use this method).
Then do any additional work 32bit doesn't support if necessary. Then save the image you're happy with to a lossless format like TIFF for archival.
Next, either:
1: Open "Save for Web" and experiment with the settings while watching the preview to see what you are happy with. For PNG, make sure you use PNG-24, or you might just as well use GIF.
2: if you want to do it manually, change the image to 8 bit/channel for JPEG/PNG or indexed color for GIF. Save the result directly checking the final image afterwards for JPEG to see if you put the quality at a good level,


My preference is:
JPEG for realistic renders/photographs/highly detailed images with lots of colors/no transparency
PNG for high quality graphics that require transparency, vector graphics, logos and so on
GIF for simple vector graphics, small animations

Also, you might consider converting to sRGB for regular computer monitors.