I'm trying to render a scene in a size big enough to practice some postwork, hair painting and such. At first I had it too small, so when I painted with a one pixel brush, it looked like I was painting with a lincoln log. Then someone suggested I render it really big to paint on and then resize. I tried to do 4000 x3000 at 72 dpi. It came out all pixely - if that's a word. Anyway it looked like the very dickens.. so my question is this. What Is a good size and resolution for rendering with post work in mind.

thanks,
myst

It sounds like you're saving the render as a jpeg, instead of an uncompressed image such as a tif, if it's looking pixellated. You must save a render in an uncompressed format if you intend to do post processing on it. Saving as a tif will also give you an alpha channel if you need it, for compositing purposes. The dpi doesn't matter at all, unless you need to print it.

Thanks, rubicon. hmm.. I usually save as a png, I bet I just  messed up and did a jpeg the last time...

I'd still love to hear folks opinion on a good size to work on for postwork, as well.

myst

Did you resize or crop the image before you started your postwork ? The dimensions you mention are fine for postwork, even with a png file. Even a jpg file would be ok, unless you had the quality setting very low.

The default quality setting for JPG is unusably low (25, if I remember it right). That still catches me out sometimes, late at night when I should really be in bed but I'll just try one more render... :) I usually save to PNG, which has the advantage of a transparent background. When I do switch to JPG I have to remember to jack the quality setting up too. Why it can't be a global preference setting like every image editor I've ever used, I don't know. - Edit - Sorry, I avoided answering your question in favour of a rant. :) If I'm going to postwork, I usually save at twice the intended final image size. To be fair, I don't do painted hair so the requirements for that could well be more demanding.

I always render at  at least twice the pixel resolution that I want the finished piece to be (meaning I usually render at 3000-4000 pixels square), then save  as psd for postwork in photoshop as that also saves the alpha channel. Most post work is done at a magnification of x2 and often x4 if what I need to do is particularly fiddly.

And P7 has the nice feature of saving at least your last render, so you can just hit the Render tab at the top and resave your Render, without having to rerender ^ ^

thank you, everyone! Now, next question, when you resize it after postwork, do you loose detail?

myst

To an extent, but a picture rendered at 3000 pixels square and then reduced to 1500 will still be sharper/hold more detail than a picture rendered at 1500 to begin with.

Quote - To an extent, but a picture rendered at 3000 pixels square and then reduced to 1500 will still be sharper/hold more detail than a picture rendered at 1500 to begin with.

And how do you figure that, as in order to reduce its size to half, you're throwing information out?

One reason being that  at a high resolution textures are rendered in a lot more detail. I find that even when reduced they are sharper and more defined than they would be if rendered directly at at whatever resolution.

Quote - And how do you figure that, as in order to reduce its size to half, you're throwing information out?

You're always throwing info out when you do a render, as usually textures in a scene are rendered at lower then native rez. So the question of 'quality' is simply that of how good your renderer is at resizing images and AA. FFly is, unfortunately, not very nice at this, certainly a lot worse then Photoshop. So if you render large enough that your textures are near native size then resize down in Photoshop you will get better and sharper results.

But this also means that there is no point in rendering larger then your textures. So eg if your scene mainly has 1k x 1k textures and they take up half the screen, anything more then a 2k x 2k render is a waste.

I got nipped by that default 25 compression too many times, so I changed it by editing Messages_JPG.txt, changing the line "Low Quality 25" to "Default Quality 100" 

//...........................................
//FileFormatIn_JPEG 24
JPEG
//...........................................
//FileFormatSaveMenu_JPEG 0
Default Quality 100
Low Quality 30
Low Quality 40
Medium Quality 50
Medium Quality 60
Medium Quality 70
High Quality 75
High Quality 80
High Quality 85
High Quality 90
High Quality 95
Max Quality 100

I hadn't realised you could do that, thanks medzin. I'd assumed the text for the dialogue box was in a file so it could be changed easily for different language versions. It never occurred to me to try editing it.

Thanks everyone, this is all very helpful!

myst