Metamerism

In article , " snipped-for-privacy@hotmail.com" writes

Nope, it's still the manufacturer's fault for not using paint that's not spectrally colour matched (see last para). In theory, using the same pigment as the original should do that, though some pigments may be no longer available, and I suppose the medium could have some effect.

David

Given the stories of how colours were actually mixed and applied (not the theory), that's simply not possible IMHO.

MBQ

The primary factors in colour perception are a) your physiological quirks and glitches; and b) the ambient light.

Regarding a), the only thing we can ever be sure of that we see the same (or at least closely similar) colour _differences_. We may infer that we see more or less the same colours, ie, that the experience of colour is generally the same for us all, but objectively, we can test only the perception of differences. (BTW, women in general can discriminate finer colour differences than men.)

Regarding b), this is so complicated that we all make mistakes, mostly because we confuse our perception of colour with the objective reality. People often talk as if seeing a colour outdoors will give them a true impression, forgetting that the objects in question (clothes, train models) often aren't intended for use outdoors, and in any case it's unlikely that they'll be seen in exactly the same weather and lighting conditions in which they were tested for their "true" colour.

There's another, somewhat counterintuitive, factor: we see the colours we expect to see, even when the ambient light does not provide a full spectrum, or the paint composition doesn't reflect the correct mix of colours. Only in severely deficient light (eg from mercury vapour lamps) do we realise that we are seeing some colours incorrectly. Most of the time, we correct our perception of the colours, even the colours in shadows, which are spectrally not the more or less neutrally grayed colours we perceive.

The visual cortex is remarkably subtle creator of illusions, all of them unnoticed almost all the time, because they serve to create a "correct" image of the world around us. Once in a while, we do notice these corrective illusions, and then we marvel at the weirdness of the world. We should perhaps rather marvel how much of that weirdness we eliminate without being aware that we do so.

cheers, wolf k.

Most colour pigments used in the past faded with age, so any given steam loco or passenger carriage would vary year by year. (actually, quite a lot of Diseasals have done that as well :-) Some colours were more prone than others to rapid fading. If we painted our models in precisely the shades the prototype left the works as, we would be wrong for most of the working life of that item. Add to that the fact that colours look lighter with distance - 76' away looks appreciably lighter than at 1' ...

There are so many variables that any shade lighter than original will be right at some point between prototype repaints ;-)

Greg.P. (nobody mention black)

Thats why I prefer the Hornby colours and finish on their locos to Bachmann. Bachmann look as though just been painted/varnished whereas Hornby more well cleaned.

Cheers, Simon

I reckon there's a lot of room for subjectivity with colours. About a month ago I painted an Express Parcels SPV with Railmatch aerosol BR blue. It looks just the part.

Yesterday I put the final coat on a 08, and it looks way too dark - despite both having a coat of primer, and then 4 coats of blue (I go very carefully with spray paint!).

If I take a photo of the two, they look the same, but something (amount of details maybe) makes the 08 look darker. It could be brass vs. plastic I suppose!

I've also noticed a number of BR blue preserved diesels where the yellow is completely wrong (far too yellow if you see what I mean), particularly one at High Peak.

The trouble is I'm a bit dubious about relying on photo's these days, unless there is a something to reference against, as so many are messed about with to make the photo look nice rather than be an accurate record.

Just some random thoughts!

Cheers Richard

beamends wrote: [...]

Well, if you sued the same primer on both models, there shouldn't be that much visible difference. OTOH, even a small difference in objective shade or tone can translate into a large difference in how the camera and the human see colours. Firstly, we see much wider range of light and dark than film or electronic sensors do. Thus, a small difference in shade can become a large difference when photographed. Secondly, there is automatic correction of tone, hue, and shade to make "the same colours" actually look the same. This correction starts in the eye. By the time this automatic correction system has finished its work on the inputs, you will see more or less what you expect to see, in this case an 08 and an SPV that are the same colour. Or close to it.

IMO, that's because they are painted using aged oil-based colour chips for reference. But those chips (stored in cupboards etc) have darkened with age (that's also the reason "old masters" paintings have darkish all over tone.) What we mostly recall is working locos. The yellow faded _very_ quickly. Well, actually, the medium breaks down, and a thin layer of semi-opaque whitish dust overlays the yellow, if you want to be technical.

You're quite right to be dubious, and I think you should be even more dubious about old photographs. What you recall and what the camera saw are quite different. Film is even more sensitive to differing ambient light than digital. Digital cameras have software that corrects the "white balance". All current cameras have settings for different kinds of light sources, too. So in fact, a digital image is, in one sense, more correct than a film image.

IMO, many modellers fuss too much about the "correct" colours.

cheers, wolf k.

Exactly! A swiss photo of mine demonstrates this rather well

although clearly there is a dirt effect here as well as fading!

I am wondering if the whole perception of colour rendition is down to our ageing.A few weeks ago I saw something on telly about eyesight and how the level of lighting needs to be increased as you get older. When you are aged 40 to 55 you need twice the amount of lighting as before

40 and above 55 you need three times. It also said that so many bulbs do not give you the same brilliance as sunlight. Strip lights are one of the best light sources but I know this affects a lot of people because of the slight "flicker". Another factor that a lot of people do not realise is that net curtains subdue a lot of the suns natural light which can be up to one of the ageing factors.

Another factor that is seriously affecting our perception of colour is the amount of TV screens and computer monitors that are not now correctly set. A friend of mine worked at a television tube manufacturer a good few years ago and they had reference photographs to set the correct colour balance of a device. In the old days we used to have the colour test card displayed on the TV screen whenever there was not transmission of programs and there were reference photographs to set the correct colour balance/lighting. Progress has improved things but some standards have diminished.

Ian Robinson

Many people do not read the instructions on how to set up their TV for different types of prgramming and different levels of room lighting. They are often set up to look good in a brightly-lit store alongside other screens, and may be too bright and saturated for home viewing.

As was saying the other day, colour especially in weathering and adding rust should always change shade gradually merging from one to another over a distance. Tonight was looking at a colour photo of an ex wd 2-8-0 in old backtrack that has large patch of rust on smokebox that looks as if its been painted on, has sharply defined edge with no transition whatsoever. Few other patches around, not as dramatic but also well defined edges. What do I know ? If had seen someones model weatherd like that would have smiled knowingly think oh dear.... Suggest work from photos of what you would expect rather than just any example.

Cheers, Simon

Try modelling pre-grouping - that way you will never know if you are wrong (therefore you are presumably right) but you can still argue with the terminally pedantic. ;-)

Way back when I first got colour TV, one of the first things I noticed was that in general UK colour programmes had 'more realistic' colours than US colour programs, which tended towards the gaudy.

Greg.P. NZ

Obviously one needs a little photograph wallet by the layout with copies=

of the photographs one sourced in weathering one's locos. :-)

Greg.P.

Oh I don't know, there's "experts" on everything out there......;-)

I'm not a steam type, but I do have a sneaky desire to build a 9F ( I had one on my all diesel 00 layout when Hornby first made them). If I ever do build one I will paint it like chap on NRM forum - BR blue, with the Arrows Of Indecision on the smoke deflectors. Because it looks nice. And as a bonus it would annoy the purists ;-)

That would be Just Wrong. The Arrows need to be white or silver, and wouldn't show up at all well on yellow smoke deflectors.

Large Logo, of course...

Someone had a load of such pix (Can I find them? No...), and ISTR that Network SE suited the Spam Can rather well.

Tim

I found it difficult painting pre-grouping passenger livery, which is why my Big Layout was a freelance light railway (drawing on the Madder Valley and the Garstand and Knot End Rly), that way I could use simplified livery for the coaches, this also meant I could use outside cylinder chassis from continental engines which at the time were better runners).

Regards

Mike

NTSC was always a bit problematic, when the Germans developed PAL things improved a fair bit and the UK was lucky in being late to the party as we got to pick.

Regards

Mike

NTSC stands for "Never the same colour", so popular rumour has it.