GIMP Limitations

[gaystan]

Hi everyone :

 I just discovered a limitation of GIMP  2.10.   Whenever I import a .jpg file (either as a background or as a LAYER), the SHADOW  tool won't work.  But.....when I use the TEXT tool,  I am able to use the SHADOW tool.  One reason is....that the TEXT tool is an internal tool. Whereas, importing a .jpg file works on the basis of being external.  
garystan

[PixLab]

(06-16-2023, 04:49 PM)gaystan Wrote: Hi everyone :

 I just discovered a limitation of GIMP  2.10.   Whenever I import a .jpg file (either as a background or as a LAYER), the SHADOW  tool won't work.  But.....when I use the TEXT tool,  I am able to use the SHADOW tool.  One reason is....that the TEXT tool is an internal tool. Whereas, importing a .jpg file works on the basis of being external.  
garystan

Nope, not at all.
the shadow filter will use transparent part of a layer, that's why the shadow filter does not work on an imported jpg, because there are no transparencies, not a gimp limitation.
Now add an alpha channel to that jpg, erase some part on that jpg, and use the drop shadow filter, you will see it works.
Also by default, the drop shadow does not work outside of the canvas (thus outside of the jpg from your point of view), unless you make all visible or increase canvas size, still not a gimp limitation.

[rich2005]

More examples of the same. 

A jpeg image does not support transparency, you can add transparency and maybe grow the layer and the GEGL filter will work. Otherwise the old legacy drop shadow is still there and that adds its own transparent layer underneath for the shadow effect.

   

...but then when there is transparency, using say a png image the GEGL filter works on that layer. What is the advantage over the old filter ?  The GEGL filter draws directly on the canvas for you to adjust in real time.

   

[gaystan]

(06-16-2023, 05:40 PM)rich2005 Wrote: gaystanLabHi everyone :
[quote pid='34894' dateline='1686934169']

 I just discovered a limitation of GIMP  2.10.   Whenever I import a .jpg file (either as a background or as a LAYER), the SHADOW  tool won't work.  But.....when I use the TEXT tool,  I am able to use the SHADOW tool.  One reason is....that the TEXT tool is an internal tool. Whereas, importing a .jpg file works on the basis of being external.  
garystan

Nope, not at all.
the shadow filter will use transparent part of a layer, that's why the shadow filter does not work on an imported jpg, because there are no transparencies, not a gimp limitation.
Now add an alpha channel to that jpg, erase some part on that jpg, and use the drop shadow filter, you will see it works.
Also by default, the drop shadow does not work outside of the canvas (thus outside of the jpg from your point of view), unless you make all visible or increase canvas size, still not a gimp limitation.
[/quote]

Which proves my point. Because GIMP won't accept .jpg files, that is considered a limitation of the software.  GIMP "programmers" should put together a plugin for thisd.
garystan

[Ofnuts]

(06-17-2023, 04:23 PM)gaystan Wrote:

(06-16-2023, 05:40 PM)Pixlab Wrote:

(06-16-2023, 04:49 PM)gaystan Wrote:  I just discovered a limitation of GIMP  2.10.   Whenever I import a .jpg file (either as a background or as a LAYER), the SHADOW  tool won't work.  But.....when I use the TEXT tool,  I am able to use the SHADOW tool.  One reason is....that the TEXT tool is an internal tool. Whereas, importing a .jpg file works on the basis of being external.  
garystan

Nope, not at all.
the shadow filter will use transparent part of a layer, that's why the shadow filter does not work on an imported jpg, because there are no transparencies, not a gimp limitation.
Now add an alpha channel to that jpg, erase some part on that jpg, and use the drop shadow filter, you will see it works.
Also by default, the drop shadow does not work outside of the canvas (thus outside of the jpg from your point of view), unless you make all visible or increase canvas size, still not a gimp limitation.

Which proves my point. Because GIMP won't accept .jpg files, that is considered a limitation of the software.  GIMP "programmers" should put together a plugin for thisd.
garystan

You don't need a plugin. In "Preferences" there is a setting to add an alpha channel when you load an image without one (like JPEG). Use at your own risk, because if you export back to JPEG the alpha channel will be removed since the JPEG format doesn't allow it. And the restriction only applies to the base layer. Any layer you add over it will have an alpha channel and can have a drop shadow.

You'll also find that the drop shadow doesn't work as you think in GIF. Also a problem with GIF, where the alpha channel is "binary" instead of progressive like in PNG.

[PixLab]

(06-17-2023, 04:23 PM)gaystan Wrote: Which proves my point. Because GIMP won't accept .jpg files, that is considered a limitation of the software.  GIMP "programmers" should put together a plugin for thisd.
garystan

Your point of view proves nothing, but what your answer proves is that you have a misunderstanding about image format and alpha channel > nothing to do with a pseudo GIMP limitation, and BTW GIMP accept jpg