Scratch

hmnwilson · 2007-12-15 22:45:54

I sort of overuse the gradient effect in my projects, but I like to make them look good and almost 3D. Anyway, after downloading 1.2.1, I made a game and saved it. but when I re-opened it, the gradient effect looked really bad! It looked like a bunch of different colored bars stacked on top of eachother. I'm guessing it got compressed when I saved it but I didn't want it to. Is it supposed to do that or is it a bug? If it's supposed to, could you take that out in the next version? (I'm still using 1.1 because of that, but I want to be able to use the new features, too.)

MyRedNeptune · 2007-12-16 01:14:44

The ghost effect disappears when the project isn't running. Have you got a When flag clicked, set ghost effect to ----- script?

johnm · 2007-12-16 21:57:08

Hi, hmnwilson.

Scratch 1.2.1 does automatically compress some images when it uploads them--but only in the uploaded copy of the project. It doesn't compress images in your local version of the project unless you run image compression manually.

If you want to upload a project without image compression, just uncheck the box on the share dialog that says "compress sounds and images".

Give that a try when you have a chance and let me know if it helps.

Could you tell me which project has a gradient that looks bad when uploaded with 1.2? I would like to check it out. The compression setting is very high quality so it should look too bad (but you may just have a very keen eye for such details).

-- John

Last edited by johnm (2007-12-16 21:59:51)

hmnwilson · 2007-12-19 19:10:27

I haven't uploaded any projects with v1.2.1.
This was made before saving:

(sorry about the white line at the top)
and after saving + re-opening:

Not uploaded.

Last edited by hmnwilson (2008-05-07 19:52:20)

kevin_karplus · 2007-12-20 00:59:56

Heavy jpeg compression is known to produce false contours on smooth gradients. It is probably worst on color gradients.

johnm · 2007-12-21 10:54:06

Hi, HMWilson.

Thanks for the examples.

You are right, the colors are getting banded when the project is saved or uploaded with Scratch 1.2.1. This did not happen with Scratch 1.1. It's the result of some code I added very late in the release cycle to minimize project size. The optimization was supposed to be "lossless" but, as you discovered, it is not--it's ignoring the least signicant few bits of the color information. This bug is my fault (and a reminder to not add "improvements" at the last minute). Thanks for catching it.

I will fix this for the next release. But since we just had a release, the next one may be many months away. Meanwhile, you might want to to stick with your Scratch 1.1 and not upgrade to 1.2.1.

FYI, the JPEG compression automatically applied when sharing a project is very light--level 90--which should not cause any noticable banding. (More extreme JPEG compression--say levels below 20--can result in very obvious banding, as Kevin says).

But this problem is unrelated to JPEG compression; it is a separate optimization that tries to reduce the image color depth to save space. There is no manual way to disable it, but images with more than 256 really different colors (like most photographs) will not get optimized.

-- John

Last edited by johnm (2007-12-21 10:59:54)

bigB · 2008-06-06 09:26:16

theres no chance of you releasing a new version of scratch that solves this problem earlier even if it changes nothing else about version 1.2.1 is there?

hmnwilson · 2008-07-29 23:30:09

I recently found 1.3 beta [link removed by moderator Jens], and the problem wasn't fixed... please fix it in the full version of 1.3.
big_smile

Scratch

archived forums

#1 2007-12-15 22:45:54

1.2.1 bug

#2 2007-12-16 01:14:44

Re: 1.2.1 bug

#3 2007-12-16 21:57:08

Re: 1.2.1 bug

#4 2007-12-19 19:10:27

Re: 1.2.1 bug

#5 2007-12-20 00:59:56

Re: 1.2.1 bug

#6 2007-12-21 10:54:06

Re: 1.2.1 bug

#7 2008-06-06 09:26:16

Re: 1.2.1 bug

#8 2008-07-29 23:30:09

Re: 1.2.1 bug

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