Gradient test

[xtknight]

Originally posted by: SonicIce
http://users.ameritech.net/xzz/grad.png this should be quite obvious

Yeah, those are some big steps. Unfortunately the algorithm really falls apart as you make things bigger. I'll see what I can do though.

 

[SonicIce]

how did you do that alternating color thing?

 

[Zebo]

No stepping on both bottoms using NEC "IpwnU" 20WMGX2... tops seem stepped about every 2mm consistantly from right to left.

Edit Just tested on DiamondPro.. looks the same as LCD did.

Edit 2 Tried on Dell 2005 no discernable difference between top and bottoms.

Edit 3 Tried on my Sony Laptop same thing...

 

[kmmatney]

I once submitted some color gradient VB code to planet-source-code back in 1999. It's a little Visual Basic program (all source code included) that calculates 2D math equations and displays them with various color gradients. I have a few of my favorite "preset" gradients in a combo box, but you can mix and match any colors in a 2 or 3 color gradient.

http://www.planet-source-code.com/vb/sc...s/ShowCode.asp?txtCodeId=2515&lngWId=1

The program was done a while back and not very efficient, but kind of neat. The algorithm is used for the tiny plots at the top of my companies website: www.bede.com

 

[Tifosi248F1]

If I get up real close I can see the steps in the top on my 2070nx using DVI. The bottoms look fantastic even up close.

 

[CP5670]

I see quite a bit of banding on the top bars with a CRT on VGA, basically the same thing everyone else described. It's particularly noticeable around the dark ends of the gradients. The top bars in the yellow and gray images seem to exhibit it about equally, but the bottom yellow one has a slight amount of banding if I look at it carefully (at the dark end) while the bottom gray one looks almost fully smooth.

 

[scroller52]

for me, the gray and smoother than the yellow scale.
its barely noticeable, but if u look hard enough, i can see the differences
i got the same results on my 2 monitors
19" nec multisync fe991sb and the 22" acer al2216w

 

[kmmatney]

Just for fun, I downloaded my old gradient program, and rewrote it to do a color gradient across the window, like XTKnight's old color gradient program. You can customize from a 2 color to a 5 color grade. You can also set the number of "Bands" to use. The window is resizable and the gradient is recalculated on the fly as you resize the screen.

The executable and source code (VB 6) are at:
http://home.comcast.net/~kmmatney/Gradient.zip

You need the VB6 runtime to run the executable - most computers will have this.

 

[kmmatney]

To my eyes, on my LCD, the grey looks a little bit smoother, but the honest answer is that I can't really tell the difference. Acer 22" LCD in sig and DVI connector

 

[xtknight]

Originally posted by: SonicIce
how did you do that alternating color thing?

Here's the algorithm I used to make the bottom yellow gradient in the OP in semi-readable pseudocode:

i = 0
currentColor = 0 ' incremented from 0-255
currentStep = 0 ' current horizontal pixel position
stepSize = 6 ' pixel width of each step of color

For currentColor = 0 to 255
..If ((currentColor=0) or (currentColor=255)) Then
....For i = 0 to stepSize-1
......' No algorithm
......Paint currentStep+i, RGB(currentColor,currentColor,0) ' yellow=red+green, blue channel is zero for i=0,i=255 (pure colors)
....Next i
..Else ' 1 (less than) currentColor (less than) 255
....' Use algorithm for colors 1-254:
....Paint currentStep, RGB(currentColor-1, currentColor-1, 1)
....Paint currentStep+1, RGB(currentColor, currentColor-1, 0)
....Paint currentStep+2, RGB(currentColor-1, currentColor, 0)
....Paint currentStep+3, RGB(currentColor, currentColor-1, 1)
....Paint currentStep+4, RGB(currentColor+1, currentColor, 0)
....Paint currentStep+5, RGB(currentColor, currentColor, 0)
..End If

..currentStep = currentStep + 6 ' increment currentStep by six pixels
Next currentColor

 

[xtknight]

Originally posted by: kmmatney
Just for fun, I downloaded my old gradient program, and rewrote it to do a color gradient across the window, like XTKnight's old color gradient program. You can customize from a 2 color to a 5 color grade. You can also set the number of "Bands" to use. The window is resizable and the gradient is recalculated on the fly as you resize the screen.

The executable and source code (VB 6) are at:
http://home.comcast.net/~kmmatney/Gradient.zip

You need the VB6 runtime to run the executable - most computers will have this.

Whoa...that's pretty cool. I'm going to see if I can add smoothing to it. Thanks for that, I'll post the source code of my program soon as well.

 

[brikis98]

i see roughly the same amount of banding (esp when looking closely) on both my CRT at home (Sony fw900) and my LCD at work (NEC 1970NX). For some reason, at a brief glance, I actually notice it more on the bottom bar, but upon closer inspection, they are pretty much the same.

 

[EKKC]

some banding for me on DELL 2407FPW

 

[Slammy1]

Actually, I see more banding in the gray scale but both show significant amounts. I wonder how many people have calibrated the contrast.

 

[EKKC]

this is so weird, im playing around with my 2407FPW (A02)'s OSD settings now, i lose all banding on DESKTOP mode, i get some banding on Multimedia mode and serious banding issues in GAMING mode. what gives?

 

[Dethfrumbelo]

Originally posted by: EKKC
this is so weird, im playing around with my 2407FPW (A02)'s OSD settings now, i lose all banding on DESKTOP mode, i get some banding on Multimedia mode and serious banding issues in GAMING mode. what gives?

Different contrasts/brightness for different modes.

The top strip should look banded if your monitor has decent enough color and contrast. The bottom strip should look smooth. If the top looks smooth or the bottom banded, then I'd say your monitor isn't producing accurate color.

 

[JRW]

On both images I can see a slight banding effect on the top portion while the bottom half looks smooth, Sony FW900 CRT.

 

[SpeedZealot369]

e1505, clearly my new laptop has some banding issues oh well I don't really care

-SZ

 

[JBT]

Dell 2405 rev A01 over DVI. The bottom looks much smoother on both yellow and grey.

 

[Zebo]

Just tried on another IPS I have.... an old NEC 1920NX... No stepping on both bottoms, tops seem stepped about every 2mm consistantly from right to left. ... no banding.. DVI hookup

Funny thing I never even used this monitor and forgot about it in garage... ordered it about three years ago..looks good xkight but of course totally unsuited for games... this was my first LCD and went straight back into box. You think 3 years is too late for RMA?

 

[LittleNemoNES]

The top one is very lightly stepped (using standard mode and Adv. DV mode on)
The bottom one is almost perfect.

Same for the yellow one.

 

[ForumMaster]

all smooth for me. i am running a no-name PolyView 17" v372 LCD on DVI with a 6600 AGP.

 

[xtknight]

Originally posted by: EKKC
this is so weird, im playing around with my 2407FPW (A02)'s OSD settings now, i lose all banding on DESKTOP mode, i get some banding on Multimedia mode and serious banding issues in GAMING mode. what gives?

Thanks for the 2407WFP results. The multimedia/gaming modes use ACC (adaptive contrast control) and put a gap in the middle of the gradient to increase the contrast between light and dark. That gap causes a lot of ugly banding. Same thing happens on my NEC in that mode. The banding is atrocious. Standard and Desktop mode (for NEC and Dell LCDs respectively) should have very few, if any, issues with banding.

It proved difficult to take a sample of three pixels and apply a smoothing algorithm to them. The less pixels you're required to input, the more parts of an image you're able to smooth out and the greater the flexibility. But three pixels isn't a lot to work with so there has to be some sacrifice. After looking through all 5,832 ((3*3*2)^3) 3-pixel algorithm possibilities, none looked as refined as the ones hand-picked in the OP using six pixels. My goal is to be able to apply this to any gradient using the least number of inputs as possible.

I hope to be able to make a program to smooth out images. It will search and stop when it hits three or four consecutive values. It will then smooth those using the algorithm and loop through the rest of the image. In the end the image will have less banding on high-contrast LCDs/CRTs but it will look just the same on average monitors. That will of course require further studying of banding and whether it's even visible on the pictures to begin with. It would be really cool to just make banding/gradation a thing of the past from movies, etc. No guarantees there though. It's no substitute for 10-bit color depth but I can't see that coming any time soon at a reasonable cost.

Originally posted by: Zebo
Just tried on another IPS I have.... an old NEC 1920NX... No stepping on both bottoms, tops seem stepped about every 2mm consistantly from right to left. ... no banding.. DVI hookup

Funny thing I never even used this monitor and forgot about it in garage... ordered it about three years ago..looks good xkight but of course totally unsuited for games... this was my first LCD and went straight back into box. You think 3 years is too late for RMA?

Why are you going to RMA it? Refund? Good luck with that. From the results that sounds like a pretty high-contrast LCD though.

 

[xtknight]

Originally posted by: SpeedZealot369
e1505, clearly my new laptop has some banding issues oh well I don't really care

-SZ

Really? I'd be surprised if a laptop showed banding. I'll have to check out my friend's e1505.

 

[Hello3]

Dell e207wfp, vga, the tops and bottoms of both the black/yello and black/white look smooth. Unlike the higher end Dell panels this one doesn't have any modes to switch to so that's all I can test. Looks good =).