One pixel line missing in Snaphots

[filouk]

There is a flaw in the ZsNes Snapshot system that I was hoping would be corrected in the new 1.50 version, but that is not the case. When you take a Snapshot and then you look at it carefully you notice that there will be one black pixel line either at the bottom or ar the top. This is not important of course, but here is the real problem : the very first horizontal pixel line from the bottom is always missing : that means you can never see the very bottom of the screen you're trying to photograph. I am making some video game maps and because of that problem I never get a perfect 224 or 256 or 512 or 1024 height, because I just can't get the line at the very border of the map. This problem occurs whatever the video mode might be. You can verify that a line is indeed missing by using the little program BgMapper, which in the countrary shows this last pixel line flawlessly. Of course you can tell me :"Why don't you always use BgMapper to make your maps ?". The answer is, I sometimes need sprites in my maps, and only a snapshot can keep them.

Could that be corrected easily ? Thank you very much.

[Johan_H]

The devs are aware of this issue, that's about all I know.
Use the Print Screen key.

[Deathlike2]

I'm not sure if the top is truly fixed. However, the bottom line is supposed to be semi-junk data (this in intentional, because not all TVs would prevent you from seeing that line).

[filouk]

Well on the maps I'm trying to create I can assure you that the bottom line is not "junk" : it is just a part of the map. If I use the PrintScreen button do you think the result will be as accurate as with the ZsNes snapshot system ?

I tried with the PrintScreen command and now there are two line missing ! They appear in black instead. This is the way ZsNes displays it.

[Johan_H]

Without filters and stretching, yes.

[Deathlike2]

Well on the maps I'm trying to create I can assure you that the bottom line is not "junk" : it is just a part of the map. If I use the PrintScreen button do you think the result will be as accurate as with the ZsNes snapshot system ?

You clearly are not reading what I wrote.

Read this for reference: http://board.zsnes.com/phpBB2/viewtopic.php?t=4346

[filouk]

Yes I read what you wrote.

But my question is : are you planning to correct this display bug ?

[Deathlike2]

The top line, probably. The bottom line, not sure.

[creaothceann]

You can verify that a line is indeed missing by using the little program BgMapper, which in the countrary shows this last pixel line flawlessly.

Try vSNES.

[filouk]

Wow creaothcann, vSnes is wonderful ! I will do great work with it !

However there is a little glitch with the scene feature : when you save the same scene twice in a row, without touching anything between the two times, then this second bitmap as well as the others will be corrupted : first, the "preview" program of Windows XP can't read them, and second, the top line is corrupted (appears in black mostly).

Also, if the "scale 256 to 512" option is checked, this is slightly different :
1. The corrupted files will not work with the "preview" program of Windows XP
2. the right half of the screen will be on the left and the left half will be on the right

Funny.

[creaothceann]

when you save the same scene twice in a row, without touching anything between the two times, then this second bitmap as well as the others will be corrupted: first, the "preview" program of Windows XP can't read them, and second, the top line is corrupted (appears in black mostly).

What format are you using for the saved files? Does it also happen with copying to the clipboard?

I have the preview function disabled.
(I guess you mean the program that starts when you open the image, not the folder's preview.)

Also, if the "scale 256 to 512" option is checked, this is slightly different :
1. The corrupted files will not work with the "preview" program of Windows XP
2. the right half of the screen will be on the left and the left half will be on the right

[Deathlike2]

Lots of stuff using the preview feature in XP have problems period. Don't rely on them.

[filouk]

Well the pictures not being read by XP's preview feature is not the problem. The problem is that when you open them with any picture software, you can see that the top pixel line is corrupted. The first time you save, this doesn't happen (and also XP preview can read them).

It does it only when saving two BMP in a row, without changing anything between the two times. It doesn't do it with PGN. Also, I would like to tryp with the copy feature but I don't know where to find it, when I click on "save or copy" I can only save the file, but not copy it to the clipboard.

[creaothceann]

See the "options" tab in the options dialog window; uncheck the "save bitmaps to files" checkbox. Bitmaps will now be copied to the clipboard (in the current desktop color depth).

[filouk]

Ok, it's all right when copying to clipboard. So the problem only occurs with BMP. Try to save at least two BMP in a row, without checking/unchecking anything, and you will notice that only the 1st one is ok, but the other ones will have a corrupted pixel line at the very top, or, if you are in "scale 256 to 512" mode, they will have both halves inverted.

[creaothceann]

Offtopic is continued here.

[filouk]

And Deathlike2, if ever you fix the top line, in my opinion it would be too bad to stop here and not also fix the bottom line. I mean it would be weird to do half the job, it would leave a feeling of inachievement...

[creaothceann]

Btw. for each line the SNES loads the sprite data in the previous line. Since there is no previous line for the first line, the SNES doesn't output that one.

[filouk]

Yes it need not be here when you play. But when you want to get game backgrounds with the proper size, you want this line too. The line exists and is part of the landscape, a designer made it. You see that's not the same point of view as when you're a player.

[creaothceann]

Then you really need external tools.

Anyway - about the screenshots: The reason for the garbage at the top is that the entire picture is shifted down by one pixel, which also hides the last line of the SNES output.

[filouk]

Well, what you say is clever, but it is not true : if you take a previous version of ZsNes, the black line will be at the bottom, and however it is still the bottom line that will be missing, not the top line. The truth is I have never any problems with the top line : it is always there. And I don't understand why Deathlike2 is talking about a problem with the top line, since there is none. The problem is with the bottom line. The place of the black line has absolutely no incidence on that.

[creaothceann]

When I say "top line", I mean the first line of the screenshot (pixels 0|0 to 255|0). Bottom line is pixels 0|223 to 255|223 (counting from zero).

Here's a GIF that shows the differences: link

Note how the output between "ZSNES windowed" and "ZSNES screenshot" is different.

[filouk]

Your gif is very good at showing that the place of the black line has no incidence on the fact that the missing line is always the bottom line, which you can only see through vSnes.

[creaothceann]

Conclusion:
- ZSNES is not supposed to show the last line.
- The devs may add an option to show it.
- The location of the content in the screenshots needs fixing.

[filouk]

Conclusion :

Snes9x 1.43+ is better at taking snapshots than ZsNes

It can show the bottom line, and besides the avi feature allows you to select exactly the snapshot you want. Wonderful.