1 Pixel Bug?…Solid Fill is not 100% Solid Fill

DP
Posted By
Daryl_Pritchard
Apr 26, 2004
Views
1749
Replies
11
Status
Closed
Hello all,

I stumbled upon something that finds me vaguely recalling a mention in the past of some sort of "1 pixel" problem in Photoshop. I know even that description is vague in and of itself, so I’ll just describe what I’ve encountered:

I created a 100×100 pixel new image with a white background, selected the right half exactly (50×100) and filled that area with solid black using the Fill Tool options set at 100% opacity and 0 tolerance. The result should have been an edge-to-edge fill of RGB = 0/0/0, yet I found the color sampling in the Info palette indicated RGB = 15/15/15 for the last 1 pixel column at the left and right edges of the black-filled area.

Moreover, if the selction marquee was still active around the filled region and I reapplied the Fill Tool, that 15/15/15 value was reduced to 1/1/1 and would only "zero out" once I applied the Fill Tool once more. However, if I first deselected the area and then filled the 15/15/15 region, it did "zero out" correctly.

This behavior was seen in both PS7 and PSCS. While I don’t consider it all too significant, it nonetheless begs the question, WHY?

Does this have to do with color value errors introduced by the active marquee around a selected area?

Thanks,

Daryl
L
LenHewitt
Apr 26, 2004
Daryl,

Is your marquee set to anti-alias?
DP
Daryl_Pritchard
Apr 26, 2004
Len,

That did the trick…thanks! I could have sworn I’d already explored whether or not aliasing affected the situation, but this was something I observed on the side while exploring another question.

Thanks again,

Daryl
L
LenHewitt
Apr 26, 2004
I think that may be Markus’ problem too…
DP
Daryl_Pritchard
Apr 26, 2004
Len,

Do you ever have those days where one minute something works as expected, then not, then it does again? Well, I may be having one of those days…I just went and re-filled the area with ant-aliasing enabled and still obtained the 1-pixel errant fill. I’m in PSCS at the moment and will recheck the behavior with PS7.

OK…here’s more info: Originally I observed this behavior while creating an action, using Select All and Transform Selection to establish 50% of my image as the area to fill. Performing the selection manually, I simply used the Marquee Tool and grabbed the desired rectangular region. When the fill is applied to the transformed selection, the error is introduced; when applied to the manually selected rectangle, it is not.

Any thoughts?

Daryl
MV
Mathias_Vejerslev
Apr 27, 2004
Daryl,

I just went and re-filled the area with ant-aliasing enabled

You want to turn anti-aliasing OFF.

Feather set to 0.

Mathias
DP
Daryl_Pritchard
Apr 27, 2004
Mathias,

Thanks…but it seems there must be multiple factors involved depending upon the selection and fill technique used. In the case where I selected the area manually using the marquee tool, the anti-alias option wasn’t available. Why, I’m not sure, but I didn’t really pursue trying to figure that out at the time. And, from that observation I assumed, perhaps incorrectly, that Len actually mean anti-aliasing on the Fill Tool should be set. With that done, I did obtain a true fill edge-to-edge. I may explore this further but not tonight.

Thanks,

Daryl
L
LenHewitt
Apr 27, 2004
Hi Daryl,

What I SHOULD have said was FEATHER set to zero on the Marquee tool – but it was late at night on a machine without Photoshop installed<g>
DP
Daryl_Pritchard
Apr 27, 2004
Len,

I can definitely understand those late night thoughts…thanks for the clarification. I did have feather at 0.

Cheers,

Daryl
MM
Mac_McDougald
Apr 27, 2004
Never noticed before, but I can’t find any set of variables with the rectangular marquee where anti-alias is even an option. Is grayed out for retangular/single row/single column. Is an option for elliptical.

What am *I* missing here?

Mac
DP
Daryl_Pritchard
Apr 27, 2004
Mac,

I’d not given the question of anti-aliasing much thought yesterday, but it makes sense that any sort of rectangular selection would not be concerned with aliasing. Only non-linear selections would be affected. Similarly, it leaves me to wonder why selecting anti-aliasing for the Fill Tool allowed me to achieve a full edge-to-edge pure 0/0/0 black fill yesterday. Since the selection was rectangular, a fill should have been performed perfectly, aliasing or not.

Off to the lab…can’t get sidetracked! Ha!

Daryl
MM
Mac_McDougald
Apr 27, 2004
Oh, duh on me…

I see you were talking about the FILL TOOL anti-alias option. I was looking at rect. marquee option.

I don’t really understand the interaction between the two enough to offer anything else at this point …

Mac

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