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Author Topic: White Text on Black Background  (Read 23793 times)

32BT

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Peter McLennan

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Re: White Text on Black Background
« Reply #41 on: May 05, 2012, 12:16:38 pm »

I'm really surprised that on a photography forum there is confusion about this issue.
White text on a black backgoround is less stressful on the eyes. It's as simple as that.

"It's as simple as that"?  Really?  Who says so?  Show us some attribution, please.

Since this is a photographic site, I'll make the following argument: Our eyes are autoexposure.  There's no "manual" setting for eyes. So, a black screen with white text causes the eye's iris to open up to accommodate the large dark area, thus overexposing the white text. We all know that overexposure leads to soft images. In addition, the accommodations forces the eye to use a wide aperture, thus creating a lower resolution image of the already-overexposed white characters.  The brain has a much more difficult time reading overexposed, fuzzy type.  

Therefore, white text on a black background is more stressful to read than the reverse.
« Last Edit: May 05, 2012, 12:19:40 pm by Peter McLennan »
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OldRoy

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....one solution is to narrow your browser window to have the main text region in a roughly 3:4 portrait shape (so about square overall?), which seems to be what this site is designed for: that will reflow the text of LuLa articles closer to that 65 character ideal....

Unfortunately the minimum before cropping begins seems to be >100 characters.
Roy
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Slobodan Blagojevic

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Re: White Text on Black Background
« Reply #43 on: May 05, 2012, 12:57:29 pm »

"It's as simple as that"?  Really?  Who says so?  Show us some attribution, please...

I really do not get it when people are trying to shove their preference down somebody else's throat. I, for one, strongly, absolutely detest any web site with white background, and gravitate toward sites with dark/black ones. I enjoy Safari's Reader feature not because it is BOW, but because it automatically uses a larger font, shorter lines and, the most important part, it dims to practically black all unnecessary crap alongside the article (e.g., ads, banners, etc.).

I do not need any "scientific" evidence or "authority" to tell me so. I trust my eyes. For me, there is a huge difference between printed pages (reflective), where BOW works fine, and screens (emissive). And I will grab a pitch and fork, call for a civil unrest , cause a revolution, go on barricades, etc., if someone tries to shove down my throat his preferences! There you have it! >:(

BJL

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Unfortunately the minimum before cropping begins seems to be >100 characters.
Roy
I see that now: so part of the problem is that this site does partly follow the modern practice (which I do not like) of imposing restrictions on text layout, violating the original concept of HTML, which was that the web-site described mainly the "logical" form of the content (like "this is a heading" or "this should be emphasized") leaving to the browser (meaning both the software and the human) ultimate decisions about visual format, such as fonts, font sizes, and line-breaks.
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BJL

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Ambient lighting levels affect whether WOB or BOW is more comfortable
« Reply #45 on: May 05, 2012, 01:28:53 pm »

The argument about the iris dilating more and reducing shrpness is partially valid, and is why dark on light (like these forums; light, not pure white though) is often good ... when the reading environment is well-lit, and the eyes are adjusted to roughly the brightness level of the page background.

However, things change when reading on the screen in a low light environment, something that has little counterpart when reading reflectively illuminated material. Then, a bright white background, far brighter than the rest of the environment, can cause eye-strain, with the shifts needed between the very different brightness levels.

Let me repeat that all the eBook reading software I know offers both BOW and WOB modes, with WOB typically considered as a "night" mode, for reading in a low light environment.

In a brightly lit environment, my favorite is black text on a pale-but-not-white background ... as in this forum software!

So, a black screen with white text causes the eye's iris to open up to accommodate the large dark area, thus overexposing the white text. We all know that overexposure leads to soft images. In addition, the accommodations forces the eye to use a wide aperture, thus creating a lower resolution image of the already-overexposed white characters.
That bit about overexposure leading to soft images is not so relevant in the context of text display: photographic issues like blown highlights and compressed contrast range in the highlights are irrelevant to a purely two-tone image, where the white parts can happily be pure 100% white.
« Last Edit: May 05, 2012, 01:31:54 pm by BJL »
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Peter McLennan

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Re: White Text on Black Background
« Reply #46 on: May 05, 2012, 02:44:04 pm »

I really do not get it when people are trying to shove their preference down somebody else's throat.

So, are you defending Ray's proclamation?  Without attribution, it's an opinion, an anecdote, not a fact.

I'm not forcing any rules down anybody's throat, I'm simply offering what I think is a well-reasoned argument for my view.  No need to man the barricades.

Yet.  : )

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Farmer

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EDIT: maybe serif fonts do not need so much resolution: I just realized that Reader on my iPad 2 uses a serif font (Palatino?), and it works well even with this mere 1024x768 display. So maybe those simple, chunky sans serif fonts on websites are a hangover from VGA display resolution?

That would be about 128ppi?  I find it still a bit dodgy, but I'm sure you wouldn't be alone in finding it workable.  There's also the question of how the aliasing is rendered.  For example, remembe the Epson Photoviewers?  The later version were 4-colour LCD screens rather than 3.  That sort of technology potentially can render better aliasing through a larger gamut (though in practice I doubt it's been tailored to do so).  So I think it's a two-prong approach - resolution and display technology.  For most users, though, the quality of the screens is not significantly different, but the resolution can be so I suspect that's where the advances will occur and perhaps drive change.

As to WOB being restive, I don't find that to be the case and I think it's a little bit (OK a lot of) a stretch to declare that as some sort of universal given for photogs.  For me, there's too much contrast.  I prefer, for example, the default of this forum.  Enough contrast to be easily read but not too much to make it glaring or difficult to read for long periods and also not so bright int he background as to blind me.

Of course, as photogs, our monitors should be at more pleasant brightness levels, below (perhaps well below) 120cdm^2, that should'nt be burning out retinas :-)

For me, readability has been a revelation - partnered with my mobile devices and a Kindle account (using Kindle Apps, not the hardware), and all for free - just brilliant (bad pun, I know).
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Phil Brown

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The argument about the iris dilating more and reducing shrpness is partially valid, and is why dark on light (like these forums; light, not pure white though) is often good ... when the reading environment is well-lit, and the eyes are adjusted to roughly the brightness level of the page background.

[...]

In a brightly lit environment, my favorite is black text on a pale-but-not-white background ... as in this forum software!

I agree. In normally lit environments, black text on a light background is best for human vision, it also allows to reduce (uncorrected) eye aberrations (due to narrower pupil diameter). It also reduces background reflections from reflective surface displays (which give rise to additional eye-strain).

Quote
However, things change when reading on the screen in a low light environment, something that has little counterpart when reading reflectively illuminated material. Then, a bright white background, far brighter than the rest of the environment, can cause eye-strain, with the shifts needed between the very different brightness levels.

Well, that depends on the screen size / viewing distance. The Human Visual System (HVS) adjusts for average luminance differences over an approx. angle of 1 degree by pupil adaptation (contraction/dilation). This means that for the most part, a black text on a bright page would be beneficial for reducing eye aberrations and reduced eye strain.[/QUOTE]

Cheers,
Bart
« Last Edit: May 07, 2012, 06:42:27 pm by BartvanderWolf »
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meyerweb

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Re: White Text on Black Background
« Reply #49 on: May 05, 2012, 11:17:29 pm »

"Very funny. Wait, there are no emoticons indicating you were kidding. So you must be serious then? If so, your reading problem is much worse than feared. "

No, not joking.  LCD monitors don't flicker, unless there's something wrong with your monitor or video card. If you have an LCD monitor that shows flicker, your backlight is most probably defective.  I've got one old Dell monitor that flickers, sometimes, because the backlight is going bad. None of my newer monitors show any flicker at all.
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Slobodan Blagojevic

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Re: White Text on Black Background
« Reply #50 on: May 06, 2012, 12:25:20 am »

I was referring to Flickr, with a capital F, not flicker, of course.

Ray

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Re: White Text on Black Background
« Reply #51 on: May 06, 2012, 08:50:32 am »

"It's as simple as that"?  Really?  Who says so?  Show us some attribution, please.

Since this is a photographic site, I'll make the following argument: Our eyes are autoexposure.  There's no "manual" setting for eyes. So, a black screen with white text causes the eye's iris to open up to accommodate the large dark area, thus overexposing the white text. We all know that overexposure leads to soft images. In addition, the accommodations forces the eye to use a wide aperture, thus creating a lower resolution image of the already-overexposed white characters.  The brain has a much more difficult time reading overexposed, fuzzy type.  

Therefore, white text on a black background is more stressful to read than the reverse.


An excellent example of a flawed argument, Peter. ;D

Now it's true that the pupil of the eye dilates and contracts a bit like the lens on a digital camera in shutter priority mode. However, there are significant differences.

The eye does not attempt to equalize light intensity for a correct exposure (or an ETTR if you like) whatever the lighting conditions may be. A dark room appears dark, and is less stressful on the eyes as a consequence.

A bright sunlit scene at midday is much more stressful on the eyes, especially if there are added reflections from the sea and white sands, or shiny objects along a highway, for example.

If the pupil of the eye were to automatically dilate to fully compensate for any situation with reduced lighting, there would be no point in wearing sunglasses. Everything would appear just as bright as a result of the pupil dilating to compensate for the over all reduced brightness.

This clearly doesn't happen, and because it doesn't happen, white text on a black background is less stressful on the eyes, all else being equal of course. There are no doubt a number of factors that contribute to eye strain resulting from long hours spent reading on a computer screen, as many office workers do. Excessive brightness from the emissive computer screen is one of them.
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Farmer

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Re: White Text on Black Background
« Reply #52 on: May 06, 2012, 05:42:03 pm »

Actaully, our eyes do in fact do that, they are just limited in their range which is why sunglasses can be a benefit.  Of course, they can also be a danger - glasses that don't wrap around the sides allow significantly more UV through because the pupil dilates as a result of the overall brightness being cut by the sunglasses (as just one example).

Again, it's an issue of overall contrast because the dynamic range of the eyes is limited and if you try to make it deal with too much, something has to give (it's why, of course, you can't see in shadows when it's otherwise bright or why a torchlight can be absolutely blinding if you're coming from complete darkness.

Presenting both extremes isn't necessarily the best option :-)
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Phil Brown

Ray

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Re: White Text on Black Background
« Reply #53 on: May 06, 2012, 08:14:17 pm »

Actaully, our eyes do in fact do that, they are just limited in their range which is why sunglasses can be a benefit. 

Everything is limited. The dynamic range of human vision is considered to be quite high. Certainly greater than a single exposure from any camera. However, whatever the biological reasons for this limitation, the facts appear to be that the eyes don't always fully compensate for changes in brightness, which is why wearing sunglasses in bright light can be less stressful, regardless of any UV considerations.

The problem is, the brightness of an emissive white computer screen is a light source in itself, a bit like a normal, fluorescent or energy-saving light bulb. It tends to be much brighter than the reflected light from any object in the room, such as the reflected light from the white pages of a book.

If your computer screen, at maximum brightness were stuck on the ceiling in a dark room, it would act as a normal light source. You could read a book sitting under it.

For people who are already suffering from eyestrain due to long periods working in front of a computer screen, it is sometimes recommended that yellowish green letters on a dark green background will relieve such tress, or white text on a black backround.

Some optical companies market special glasses that are claimed to reduce or prevent computer eye strain. The concept is similar to wearing sunglasses. I believe the tinting of such glasses is a urine-yellow. I think I prefer white text on a black background.  ;D

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Farmer

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Re: White Text on Black Background
« Reply #54 on: May 06, 2012, 11:39:41 pm »

The absolute dynamic range of human vision is very large (even if we do lose colour differentiation in low light), but our instantaneous dynamic range is substantially more limited.  We can't see into deep shadows at the same time as viewing bright, sunlight areas, for example.  We can view each quite easily by themselves, but not together.  It's a flawed argument to present absolute dynamic range for human vision as factor when discussing the ability to process extremely high contrast scenes.  It is only our instantaneous dynamic range that is applicable in such cases.

Typically, human vision is said to have at least 24 stops of range in total, however instantaneous dynamic range during normal daylight conditions is generally around 10-14 stops which isn't so different to better DSLRs (but much better than compacts).  Of course, in very low light conditions our instantaneous dynamic range would be much higher, but we would lose colour differentiation.

As to whether a monitor is more or less bright than surrounds?  Well, sitting in an office as I am currently the ambient lighting level at my desk (some flouro lights above, a little sunlight through blinded windows) is around 240lx.  A white screen from my monitor (a blank word document, for example) is 185lx.  The grey that is the background to this "reply" screen is 160lx and the green bar across the top at the title is 48lx.  This monitor is calibrated to 120cdm^2 (it's an Eizo).

So, in fact, a white background on my screen is less intense than the ambient light levels in a normal office during the day.  And, interestingly, the reflected levels from a white piece of paper (just a writing pad) on my desk is 150lx which is certainly slightly less than my screen, but not by a lot.

On the other hand, if it had a completely black screen (such as found in the articles here) that measures 4lx whereas an "average" of the black screen with the white text is 25lx.  That means I have items on the screen that vary by about 6x and is about 10% of the ambient light.  The BOW reply screen has an "average" of 160lx compared to plain white of 185lx, a variation of around 0.1x an about 65% of the ambient light.

To my eyes, the BOW is far less of a strain because my eyes are not trying to deal with more than their instantaneous dynamic range.

That all said, if someone prefers WOB I'm not going to tell them they're wrong - that's their preference!

And, of course, not everyone works in a "normal" office lighting environment (although, generally, for these sorts of tasks you really do want at least these lighting levels from an OH&S perspective) - lower or bright ambient lighting levels would change things, again due to the more limited instantaneous dynamic range of our eyes.
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Phil Brown

Ray

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Re: White Text on Black Background
« Reply #55 on: May 07, 2012, 08:01:34 am »

The absolute dynamic range of human vision is very large (even if we do lose colour differentiation in low light), but our instantaneous dynamic range is substantially more limited.  We can't see into deep shadows at the same time as viewing bright, sunlight areas, for example.  We can view each quite easily by themselves, but not together.  It's a flawed argument to present absolute dynamic range for human vision as factor when discussing the ability to process extremely high contrast scenes.  It is only our instantaneous dynamic range that is applicable in such cases.

Typically, human vision is said to have at least 24 stops of range in total, however instantaneous dynamic range during normal daylight conditions is generally around 10-14 stops which isn't so different to better DSLRs (but much better than compacts).  Of course, in very low light conditions our instantaneous dynamic range would be much higher, but we would lose colour differentiation.

Of course it is. Our instantaneous dynamic range within a fixed stare is probably less than that of some cameras, especially that of the latest Nikon DSLRs  ;) . But the instantaneous dynamic range of a fixed stare does not reflect the DR experience of most scenes that we view. The eye has a very narrow field of focus and is constantly changing its angle of view as it peruses any scene.

Within a certain dynamic range, which I believe is larger than that of any camera, the eye can almost instantly change its pupil diameter, from a minimum of 1 or 2mm to about 8mm in diameter, and the brain make adjustments which leave an impression on the mind of a very wide DR that no camera can capture with a single shot.

I never mentioned absolute dynamic range. It was you who first brought dynamic range into the discussion with the comment that the limited DR of our eyes is the reason we sometimes benefit from wearing sunglasses.

In circumstances where the eye is allowed more than a fraction of a second to adjust to changes in contrast, as it peruses a scene, its DR capability will also increase. As that adjustment period increases from a fraction of a second, to a few seconds, to a few minutes, the DR within a scene, that the mind can apprehend, gradually increases up to a maximum of maybe 30 EV, or 90dB, or 30 F/stops, as in the situation of a moonlit night where brightness levels range from a very bright object reflecting direct sunlight (the moon), to deep shadows that are almost black.

Quote
As to whether a monitor is more or less bright than surrounds?  Well, sitting in an office as I am currently the ambient lighting level at my desk (some flouro lights above, a little sunlight through blinded windows) is around 240lx.  A white screen from my monitor (a blank word document, for example) is 185lx.  The grey that is the background to this "reply" screen is 160lx and the green bar across the top at the title is 48lx.  This monitor is calibrated to 120cdm^2 (it's an Eizo).

Very sensible! That means that the white of the white text on the Luminous Landscape black background is probably less than 185 lux on your monitor.

The bottom line, as I see it, is that a black screen with white text transmits less brightness to the eyes than a white screen with black text, and is therfore less stressful on the eyes. Turning down the brightness of one's monitor is definitely a good recommendation for anyone who reads a lot of black text on white. White on black is another option which, in conjunction with a low-brightness monitor, should produce even less stress in the long run.


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Farmer

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Re: White Text on Black Background
« Reply #56 on: May 07, 2012, 03:46:04 pm »

Sory, but I think that your logic here is flawed.  You are assuming that less light is less stressful.  I don't believe that's the case.

There's a reason why we have OH&S recommendations regarding lighting levels for various tasks.  Too little light causes eye strain.  Our eyes are not strained by the average office level of lighting, even though, as you note, that is greater than the white of a well calibrated monitor (of course, consumer monitors out of the box are approaching 400cdm^2 or even higher, compared to my 120cdm^2 at the office - so they're a different story).

Again, it's the contrast.  Your eye won't change due to focal changes to accomodate the full DR of WOB screens - it will set for the average light level because the screen is a fixed distance.  What will happen is as your eye moves around the screen there will be micro adjustments, of course, but the average light levels at each point of text will be very similar.  Thus, you have to deal with a very high contrast ratio and you have to deal with a very different background lighting level.  These are things that can strain an eye.

With a BOW scenario, for example, your eye is viewing somethign much closer to the ambient light levels and with less contrast within the scene, all of which means less work or effort for the eye and the total light levels are in no way stressful.

Constantly having to change aperture (dealing with varying brightness, wide contrast and high DR) will tire the eye far more than having a constant brightness, mild contrast and relatively narrow DR unless the brightness is extreme.
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Phil Brown

AFairley

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Re: White Text on Black Background
« Reply #57 on: May 07, 2012, 08:50:59 pm »

With a BOW scenario, for example, your eye is viewing somethign much closer to the ambient light levels and with less contrast within the scene, all of which means less work or effort for the eye and the total light levels are in no way stressful.

All of which is totally irrelevant to me if its is harder for me to makeout the letterforms and parse the lines of type (which it is).  It may not be a problem for you, but it is for me.  I just give up reading some of the long articles because the hassle of making out the words is just too great.  This could must be my eyes, or it could be that I spent years typesetting in graphics design shops, who knows?  It sure would be nice to have a click box on the pages to toggle between BOW and WOB.
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Ray

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Re: White Text on Black Background
« Reply #58 on: May 07, 2012, 09:29:54 pm »

Sory, but I think that your logic here is flawed.  You are assuming that less light is less stressful.  I don't believe that's the case.


Sorry I haven't been clearer. I'll try again. Of course I don't mean that less light is less stressful whatever the circumstances. If you're turning in for a bit of shut-eye, the less light the better. If one is performing a task, such as reading, one obviously needs sufficient light for the task. Trying to read in poor lighting conditions can also be stressful.

If you have calibrated your monitor so that its maximum brightness has been significantly reduced, that is obviously a measure which will tend to significantly reduce eye strain whether reading black text on a white background or WOB.

A source of confusion here may be in the definitions of white and black. These are not absolute terms, but relative terms. In reality we simply have two shades of grey.

Perhaps we could rephrase the question. Is pale grey text on a dark grey background more stressful than dark grey text on a pale grey background? I'm suggesting the answer in part depends on the degree of paleness of the grey. Of course there are other factors which contribute to eye strain, such as glare and not wearing spectacles with an appropriate magnification, or not wearing spectacles at all when one should be, etc.

In order to draw sensible conclusions from such comparisons we should attempt to keep all other variables the same so that the same pale shade of grey is used in both cases, in one case for the text and in the other case for the background.

I can appreciate that an excessively bright shade of pale grey text, at say 400cdm on a dark grey background could be more stressful to read than a dark grey text on a much less pale grey background, at say 100cdm.

But, let me ask you which you would prefer, to spend long hours reading black text on a 400cdm white background, or long hours reading a 400cdm text on a black background?

Out of curiosity, I checked the brightness levels of the white text on the Luminous Landscape home page. In Photoshop the RGB reading was just 204,204,204, for the text, whereas the white background to the picture of the Hasselblad 500 in the article "A Synthesis of History, Technology, and Art -By Richard Sexton" is 255,255,255.

That white background around the camera appears excessively bright to my eyes, and I think it's appropriate that the white text is less bright. If one were to criticise the arrangement of WOB on LL, I would say that the white text could be an even darker shade of grey. This might be less stressful for slow readers.


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Farmer

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Re: White Text on Black Background
« Reply #59 on: May 08, 2012, 12:08:40 am »

All of which is totally irrelevant to me if its is harder for me to makeout the letterforms and parse the lines of type (which it is).  It may not be a problem for you, but it is for me.  I just give up reading some of the long articles because the hassle of making out the words is just too great.  This could must be my eyes, or it could be that I spent years typesetting in graphics design shops, who knows?  It sure would be nice to have a click box on the pages to toggle between BOW and WOB.

Sorry, I'm confused.  The articles are in WOB which I'm suggesting is not as good as BOW.  And, again, I've said a few times to each their own, but for me, BOW is much better than WOB (which is what the current articles are and why I'm now using Readability and loving it).
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Phil Brown
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