Gamma 2.2 & washed out bitmaps

[Jock]

So I've tried several times in the past to implement linear workflow and gamma 2.2 in my work to various degrees of success but usually ensd up back to my old ways when i hit a problem i cant solve.

 

I've decided to try once again but wondered if you guys could shed some light on the new issue i have. Having read a post by Peter Guthrie on his blog i've started using Renihard colour mapping and it seems to be working quite well though i think i must be missing a setting.

 

Basically i'll look at a bitmap in explorer and it'll be nice and dark, i then apply it to a material and it comes out all washed out. My gamma settings are below though i have messed with them and it doesnt seem to make much difference.

 

The only way i can seem to find to rectify the issue is when you are in the window where you select the specific bitmap, is that you change the radio button from 'use the images own gamma' to 'use system default gamma'

 

Should i be doing this for every bitmap i bring in or am i doing something totally wrong?

 

Thanks

 

[Stephen Thomas]

Sounds like the bitmaps don't have a colour profile embedded in them. Try opening in Photoshop and re-saving, making sure you tick the SRGB box in the save dialogue, and see if that solves the problem. There's no harm in doing it the way you're doing at the moment though.

[DavidR]

Where are your bitmaps coming from? Are you taking them with a camera, scanning, or what? Generally, we have to prepare maps in pshop for tiling, etc., so they're automatically saved as 2.2, and my Max settings are like yours, except for "load enable state...", which I have unchecked ('cause I don't know what it is), and output is at 2.2 for .jpg and .tiff output, or 1 for exr output. Set it to 2.2 even for 32-bit tiffs, etc, -only exr and rad/hdr formats must be output at 1. I load the bitmaps normally, ie: 'use system default gamma', so I don't have to do anything differently, and the colour-mapping (f10) settings -this is the other importabt bit- is linear multiply (a default -you should start with this and use other types for 'problem' scenes, though I've never had one:), check 'use colour adaptation...', do NOT check 'linear wkflow', and the other checkboxes are up to you. Set to linear multiply, dark 1, light 1, gamma 1. See if that works for you. If you get blown-out windows, try adj. your camera exp 1st, increase interior lighting (if you have any), dial down Vray sun, etc, before switching to Reinhard, unless you just like the flatter, less saturated look for your scene. Reinhard should be a choice, not an imposition, is what I'm trying to say -I have nothing against it, and P. Guthrie's stuff is beautiful. Good luck.

[Jock]

Ok having read hrough your posts i thought i'd do a bit more testing.

 

The main map in question is a .png from an arroway texture set, and sure enough if i just click the one i want without changing any settings, its all washed out.

 

Though i then changed to just a default timber jpeg which i probably picked up from the likes of cgtextures and it comes out fine, again with every setting default.

 

To get the first one to display correctly i need to change the radio button when selecting the image for the diffuse slot, though if thats whats needed then thats fair enough.

 

It seems that when i insert the jpeg the default is 'use system default gamma' but for the png its default is 'use images own gamma'

 

Thanks for the other explanation on 2.2 it makes things a bit clearer. I'll give linear a try again as opposed to reinhard. To be honest i think a lot of my problems is due to a lack of understanding as to what i'm actually doing in so far as changing the settings. To me its simply numbers rather than having an understanding of what the numbers actually signify, if that makes any sense...

[JamesL]

You've pretty much hit the nail on the head yourself - PNG's will embed Gamma (see http://www.mywebsite.force9.co.uk/png/ for explanation, under the heading 'Extra Features') - and so need to be brought into Max with the relevant gamma loaded to show correctly. I generally make use of the Preview window when loading PNG's and flick through the gamma options until it appears correctly.

 

For more info look here - http://morris-photographics.com/photoshop/articles/png-gamma.html - great explanation.

[JamesL]

Also, for reference I think Peter G doesnt enable Gamma correction in Max and just uses the Gamma tweak in Vray Colour Mapping - then individually colour corrects each map as he imports them - I could be wrong though.

[Jock]

Thats very helpfull guys, thanks for your time.

[Crazy Homeless Guy]

Sounds like the bitmaps don't have a colour profile embedded in them. Try opening in Photoshop and re-saving, making sure you tick the SRGB box in the save dialogue, and see if that solves the problem. There's no harm in doing it the way you're doing at the moment though.

 

Unfortunately Max cannot read embedded profiles. It is a big pain in the arse for me.