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Low resolution proxy for faster previewing.

This discussion is connected to the gimp-developer-list.gnome.org mailing list which is provided by the GIMP developers and not related to gimpusers.com.

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mailman.3.1177614004.21169.... 07 Oct 20:25
  Low resolution proxy for faster previewing. Guillermo Espertino 26 Apr 23:27
   Low resolution proxy for faster previewing. Sven Neumann 27 Apr 08:17
    Low resolution proxy for faster previewing. Øyvind Kolås 27 Apr 11:58
    Low resolution proxy for faster previewing. Guillermo Espertino 27 Apr 19:15
     Low resolution proxy for faster previewing. Sven Neumann 27 Apr 20:19
Guillermo Espertino
2007-04-26 23:27:06 UTC (about 17 years ago)

Low resolution proxy for faster previewing.

I don't know if this was answered before, but I've been browsing the archives and didn't find anything (if there was a discussion about this, please point me the thread URL for me to follow it). I'm using Gimp 2.3.15 under Ubuntu Linux, with the tile memory set in 1 GB. Even though the overall speed of preview/redrawing was improved a lot in the last development versions, I still find that is difficult to work with large images, because of the slow redrawing when moving layers, switching on/off large layers and panning the canvas when zoom factor is under 100%.
In small resolutions, I have an excellent performance, but when I work with high res compositions with several layers I find this problem when I zoom them out (the brush redrawing also seems to be affected in this situation)
I think this is because the entire data is being redrawn regardless the zoom factor (and this is not critic when the zoom is at 100% because the only part that is redrawn is the visible area). I've read that other programs as Photoshop do this in a different way when zoom is >100%: using a low resolution proxy of the actual layer for the inmediate rendering, and rendering the final resolution in the background.

Is there any solution for this issue being worked or planned? For me (and other graphic designers) and for photography enthusiasts it would be very welcome.

Gez.

Sven Neumann
2007-04-27 08:17:28 UTC (about 17 years ago)

Low resolution proxy for faster previewing.

Hi,

On Thu, 2007-04-26 at 18:27 -0300, Guillermo Espertino wrote:

I think this is because the entire data is being redrawn regardless the zoom factor

That is a wrong assumption, only the visible area is being redrawn.

What's right though is that GIMP works with the image data in the original resolution and doesn't cache a scaled down version (except for the little thumbnail previews as used for example in the Layers dialog). This will change as soon as we switch to GEGL. GEGL already uses a system that deals much better with this. Just give it a try.

Sven

Øyvind Kolås
2007-04-27 11:58:04 UTC (about 17 years ago)

Low resolution proxy for faster previewing.

On 4/27/07, Sven Neumann wrote:

Hi,

On Thu, 2007-04-26 at 18:27 -0300, Guillermo Espertino wrote:

I think this is because the entire data is being redrawn regardless the zoom factor

That is a wrong assumption, only the visible area is being redrawn.

What's right though is that GIMP works with the image data in the original resolution and doesn't cache a scaled down version (except for the little thumbnail previews as used for example in the Layers dialog). This will change as soon as we switch to GEGL. GEGL already uses a system that deals much better with this. Just give it a try.

Not completely true yet. GEGL does use an image pyramid (mipmap) on top of the baselevel
for the actual display (projection). Support for working on scaled down proxies is planned and is part of the reason that the API to develop new plug-in operations is not publicly exported yet. All of these changes can happen without changing the API for using GEGL itself though.

Thus what GEGL currently provides is a view that is of much higher quality (it doesn't do nearest neighbour interpolation when zoomed out). That also needs to access less memory to redisplay a zoomed out version of the image.

/Øyvind K.

Guillermo Espertino
2007-04-27 19:15:45 UTC (about 17 years ago)

Low resolution proxy for faster previewing.

Sven Neumann escribió:

I think this is because the entire data is being redrawn regardless the zoom factor

That is a wrong assumption, only the visible area is being redrawn.

Thanks for your reply and clarifications. I meant when a large image is zoomed out. Sorry if I didn't explain myself more clearly.
I wanted to say that the actual pixels are redrawn, not just the pixels showed on screen.

So, the conclusion is that we have to wait until the GEGL porting for this, isn't it?

Gez.

Sven Neumann
2007-04-27 20:19:20 UTC (about 17 years ago)

Low resolution proxy for faster previewing.

Hi,

On Fri, 2007-04-27 at 14:15 -0300, Guillermo Espertino wrote:

So, the conclusion is that we have to wait until the GEGL porting for this, isn't it?

Right now we are concentrating on getting 2.4 out of the door. And as soon as that is done, we will start porting the GIMP internals to GEGL. You can either help with the 2.4 release or work on GEGL in the meantime.

Sven