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Fred Blogzz

Pure white background & white point

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Hi,

With ref to alamy's requirements re the black and white points of an image.

 

I have just recently invested in a photography table with a permanent white vinyl cover, (plus a black vinyl overlay). Experimenting, it does seem desirable to deliberately introduce some subtle shadows. However for the rest of the background, it seems to be impossible to obtain both a full pure white background and a black right hand triangle.

 

Has anyone ever got a submission with a white background through QC with a white highlights triangle and highlight peaks through the roof? It seems best to ask the knowledgeable people on here rather than risk losing the three stars by adopting a suck it and see what happens approach.

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I’m not sure what you mean by a black triangle. The shadow of the object?

I have struggled with tabletop forever, and have never properly conquered it. I get light bleed at the edges, and try to remember to use black flags, which helps. Simply a piece of black plastic rolled up to the sides, then later brushed out of the image.

Often if I properly expose my subject, the BG is slightly gray. If I use the white point on the BG to get pure white, the subject is then overexposed. Doing this using layers in PS, I have to brush out the subject to get rid of the light introduced by the white point action.

 

I know there has to be an easier way. I just haven’t found it, yet. I spend 3 times the PP on cutouts or isolations than I do with an ordinary image. Sometimes I just grit my teeth and do them. Just talking about it makes me grit my teeth! :D

Betty

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LIkewise I don't know what's meant by these triangles.

 

I cut the subject out and delete the background to pure white. I then adjust the levels/curves on the subject to get the result I want

 

Some of my earlier efforts are dreadful, I should delete them. Like Betty I spend many a moon on this process, preferring to use the PS pen tool to get an accurate outline without jaggies, often blowing up to beyond actual pixels to get a good line. I also try to include the drop shadow. Even after taking this trouble, it's often necessary to edit the cutout a bit to ensure smooth and realistic transitions. I have a cheap light tent and I normally use bounced flash, or north facing window light,  but typically the object just stands on sheets of white paper.

 

Cutouts can sell reasonably well though, it's probably worth the effort.

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I refer to the triangles at the left and right ends of the histogram in ACR, in this instance the right hand triangle at the highlight end of the histogram. My apologies for not being clearer.

 

I prefer window light for table top work. Often the sun is in an inconsiderate mood and mischievously dodges out from behind clouds just as the button is pressed. In these conditions I use AV exposure mode with + compensation because of the white expanse background.

 

It's early days for my tabletop stuff, but the problem is how to get a pure white background without breaching Alamy's white point requirements. To get the background pure white seems to mean going off the right hand end of the histogram and therefore having a white highlights triangle.

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QC knows what a white background is. Don't worry.

However you only want to blow out the white background not your highlights. The odd specular highlight is fine, but ideally you want to control these as well.

 

@Betty, the easier way is to use a light table and blow out the white from underneath 2 stops higher than your highest highlight. No drop shadows in this case of course and a tell tale white reflection from underneath. Which otoh some people find desirable.

 

wim

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For table top on a "white background."  First I only use NIKON D800's in RAW or NEF, then I do a custom white balance.  Then I shoot

a frame of my white card, then I shoot a frame of a color chart.  Working in LR I get my exact color temp and exposure from the white

card and from the color chart.

 

If a 255 or 100% white background is what I want I turn up the strobe a bit (1/2 or 1/4 stop).

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I posted the following in November last year, I hope this helps ...

 

If you have a look at my portfolio, you will see that almost all of my images are studio shots of objects against a white or black background. As others have said, if you want to do this well, it takes time and it is not a skill you learn overnight. Perhaps I can share a few things with you, after shooting 100+ images in this way almost EVERY DAY for the last 10 years.

 

- Make sure you separate your background from your subject by sufficient distance to avoid light spill (flash bouncing off the background onto the rear of your object)

- It helps to put a large sweep in the background, having the back hanging vertical increases light spill

- Always light your white background with a separate light source and make sure it is one stop overexposed compared with your subject, use a flash meter to check, you don't want to overexpose by more than one stop

- Every session, make sure you set custom white balance (use a neutral grey card), this will ensure your colour balance is always correct and will save you a lot of time in processing afterwards. Don't assume it will be the same every session, always start custom white balance from fresh.

- Use the highest shutter speed you can (1/250s on most cameras, unless you have a leaf shutter)

- I personally don't use a tripod, it slows me down too much, but if you use one make sure your IS (Image Stabilisation) is switched off

- Be careful what you wear if your object is reflective or you are shooting a flat object held flat with glass. Wear a black cape if necessary. Avoiding reflections is something I could write a book about!

- If you're not shooting on white, and you don't want to set custom white balance (or can't), put a small piece of white card in the corner somewhere. You can use this to set white balance later in processing if you wish.

- Shoot in RAW if you can, it will make life much easier

- Make sure you have a decent monitor and CALIBRATE it regularly

- I open all images in ACR (Adobe Camera Raw) in Photoshop CC. Make sure the chromatic aberration and lens profile adjustment boxes are ticked. If you are shooting on black or white, you will almost certainly have some (or a lot, depending on the quality of your lens) chromatic aberration (CA) to deal with.

- Use the icons above the histogram to show blown highlights and shadows. These will turn part of your image red and/or blue respectively in blown areas.

- To make the remaining areas around the subject white that aren't already blown white, I first use the white slider (not too far), and then the adjustment brush (set at +1 exposure and +5 white) to paint the remaining areas red. Start with a larger brush, then repeat reduce the brush as you get closer to the image. This is a skill that you will perfect with practice. If you have a black background, you basically do the same but using the black slider, and a brush set at -1 or -2 exposure and a negative black brush (painting areas blue).

- Don't destroy your subject shadows, these normally need to stay unless you want a complete cutout

- Correct any perspective in ACR, it is much easier to do it there. I do it by drawing 4 lines when shooting books, maps, etc.

- In extreme cases, you can use the pen tool in Photoshop CC to create cutouts (I try and avoid using the magic wand)

- Go for square cropping when possible, this maximizes visibility in searches among other images, it makes your image thumbnail "larger"

 

Marc

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Thanks for the replies folks. It appears an over exposed white background may be accepted by QC. I'll find out in due course.

 

Thanks again.

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3 hours ago, GS-Images said:

All good advice above so I won't repeat it. I'll just give a slightly different take on things if that's ok.

 

Like a lot of these things, it's common sense. The guidelines are just that, guidelines, not always strict rules. White and black points can be very obvious and completely black or white, IF it fits the image. So a pure white background (a cutout) is fine, and an image of the moon at night with pure black in the sky is fine (although some texture might be nice too but it depends on the image). Take a foggy landscape seen - Try setting black points and it'll ruin the image completely. You can't always stick to the strict letter of the guidelines with every image.

 

Alamy know what they're doing and will use common sense when looking at your images. So no need to take a risk with QC, just do what fits the image and if an area is supposed to be pure black or white, it will pass.

 

Geoff.

 

I agree with this. Very rarely do my histograms show perfect exposure limits. One can adjust exposure, reign in shadows and highlights to a certain extent but even this may not give you perfection. Therefore it is my challenge to make sure that the main subject of the image is perfectly exposed in these situations and rely on Alamy to understand what was practicable and what was not or indeed whether adjustment would have been beneficial or would have defeated the purpose of the image.  

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