Multiply mode on layers not working

whynter · **Joined:** Sep 26, 2014 **Posts:** 3

GIMP Version: 2.8.10
Operating System: Windows
GIMP Experience: Beginner Level

Hi, I am simply trying to color a sketch on gimp that I drew in Manga studio. I open the sketch in gimp and set that layer mode to "multiply" like the tutorials I have seen say to. I open the new layers on top of the sketch layer, but when I color it always covers up my sketch lines. I need them to be visible until I am done, or even after possibly, but they always get covered. How can I fix this?

molly · **Joined:** Apr 07, 2010 **Posts:** 14182

make a duplicate of your sketch, then on the duplicated layer, change to multiply mode or try different modes until you get one you like.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4812

The multiply trick works only with black lines on white background... What are the colors of your sketch?

Wallace · **Posted:** Fri Sep 26, 2014 8:12 pm **(#4)**

In addition to what Molly has suggested, you can try this.

Erisian · **Posted:** Sat Sep 27, 2014 3:51 am **(#5)**

It's not the sketch layer that needs to be on multiply but the layer you are colouring on.

Wallace · **Posted:** Sat Sep 27, 2014 10:28 am **(#6)**

Erisian wrote:

It's not the sketch layer that needs to be on multiply but the layer you are colouring on.

Yes you're correct Erisian, it can also be done this way. With the transparent layer for coloring on top of the image, with layer mode set to multiply.
This can also be done as I've described, as long as the image is in B&W in both cases.

trandoductin · **Posted:** Sat Sep 27, 2014 11:18 am **(#7)**

Wallace wrote:

In addition to what Molly has suggested, you can try this.

[ Image ]

gee, that's a good picture of dragon!

Wallace · **Posted:** Sat Sep 27, 2014 12:20 pm **(#8)**

trandoductin wrote:

Wallace wrote:

In addition to what Molly has suggested, you can try this.

[ Image ]

gee, that's a good picture of dragon!

Yes it is a rather nice looking image.

http://dracoflameus.deviantart.com/art/ ... -271630422

Marcello · **Joined:** Mar 10, 2014 **Posts:** 845

with Wallace method (Thank you)
( just 3 minutes with mouse)

Abandonet house

whynter · **Joined:** Sep 26, 2014 **Posts:** 3

Wow thanks for all the replies! My sketch was just black and white, but I got it to work by setting the color layers to multiply. Thanks so much for the help!

Wallace · **Posted:** Sat Sep 27, 2014 1:51 pm **(#11)**

whynter wrote:

Wow thanks for all the replies! My sketch was just black and white, but I got it to work by setting the color layers to multiply. Thanks so much for the help!

That's great! :bigthup

I'm glad that what we all had to suggest was helpful to you.

whynter · **Joined:** Sep 26, 2014 **Posts:** 3

One last question, is there a shortcut key to flip the image while you are working on it? I know you can go up and click to rotate it 90 degrees, is there a way to do less than that?

Thanks!

molly · **Joined:** Apr 07, 2010 **Posts:** 14182

There is a flip tool beside the perspective tool, horizontal and vertical

K1TesseraEna · **Joined:** Sep 22, 2012 **Posts:** 2089 **Location:** US

whynter wrote:

One last question, is there a shortcut key to flip the image while you are working on it? I know you can go up and click to rotate it 90 degrees, is there a way to do less than that?

Thanks!

Edit: What you need is probably a canvas rotation feature.
Gimp doesn't have this feature yet (some gimp forks do though)

To quickly transform an image on canvas
1.Flip H/V:
Shift+F to activate Flip tool.
Left mouse button (LMB) click to flip horizontally,
LMB+Ctrl to flip vertically.

2. Rotation
a) Rotate 90 degrees CW,CCW, etc. can be assigned to shortcut keys.
Just make sure in Edit>preferences>Interface under Keyboard Shortcuts you have
Use dynamic keyboard shortcuts box checked.
Then go Image>Transform>Rotate 90 (whatever), move mouse cursor over desired command to highlight it
and press the keyboard keys to assign a keystroke.
b) Using Rotation tool (Shift+R) you can press and hold the Ctrl key to restrict rotation to 15 degree increment.

Keep in mind that unlike canvas rotation (in fact rotation of the image view),
transformation operations are, in general, destructive by their nature.
Each such operation makes the application to redraw the image, hence, some loss of quality.
It's all the same for any raster editor, gimp or photoshop.
So, the more you flip the image the more information gets lost along the way.

saulgoode · **Posted:** Sat Sep 27, 2014 8:54 pm **(#15)**

K1TesseraEna wrote:

Keep in mind that unlike canvas rotation (in fact rotation of the image view),
transformation operations are, in general, destructive by their nature.
Each such operation makes the application to redraw the image, hence, some loss of quality.

Rotations of multiples of 90 degrees (90, 180, 270, ...) do not result in a loss of image quality, nor do horizontal and vertical flips.

K1TesseraEna · **Joined:** Sep 22, 2012 **Posts:** 2089 **Location:** US

saulgoode wrote:

Rotations of multiples of 90 degrees (90, 180, 270, ...) do not result in a loss of image quality, nor do horizontal and vertical flips.

Hm-m. I read that JPEGs do. And that's about 80% of the general purpose image format.

Although it's considered that GIMP or PS don't decompress them at 90 degree rotation or H/V flip,
therefore, there is no quality loss, however it's only true if the image resolution is a multiple of the 8x8 pixel block.

Most of the template sizes set in pixels do follow this 8x8 blockness rule but custom documents and docs set in
typographical points, inches, picas, shots from the digital cameras quite often don't. Is this wrong?

I also remember reading some article about PS team study on this issue and their conclusion was...inconclusive.
They weren't quite sure.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4812

As I understand it SG is right but only partially so. If the result corresponds to the same 8x8 boundaries, you deduce the compressed form of the flipped/rotated image directly from the compressed data of the original image, so there is no loss. But this doesn't happen that often (due to the 8x8 constraint) and very few application bother (I head about one called Photoline that does...).

On the other hand, the JPEG compression algorithm is "stable", if you re-compress iteratively the very same data (with the same compression parameters) you very quickly end up with identical data each time, so there are no further losses after a couple of saves(*). In other words, a local edit in a JPEG image may not create losses outside of the 8x8 blocks that are changed by the edit.

(*) Image forensics can use this "settling" of the data to detect changes..

saulgoode · **Posted:** Mon Sep 29, 2014 12:12 am **(#18)**

K1TesseraEna wrote:

saulgoode wrote:

Rotations of multiples of 90 degrees (90, 180, 270, ...) do not result in a loss of image quality, nor do horizontal and vertical flips.

Hm-m. I read that JPEGs do. And that's about 80% of the general purpose image format.

My intent was to address "images", not files. The conversions that take place when importing and exporting files into and out of GIMP may or may not cause some picture degradation; but once in GIMP, using any of the rotate* or flip comands in the "Image->Transform" and "Layer->Transform" menus does not cause a loss in image quality. For these operations, none of the pixel values are altered, only their positions change (e.g., one could perform thousands of "Transform->Rotate 90" ops without ever changing a single pixel).

* "Layer->Transform->Arbitrary Rotate..." will cause image quality loss if the angle specified is not a multiple of 90 degrees and, even if it is a multiple of 90 degrees, may cause quality loss depending upon the center's location.

Wallace · **Posted:** Mon Sep 29, 2014 12:56 am **(#19)**

saulgoode wrote:

K1TesseraEna wrote:

saulgoode wrote:

Rotations of multiples of 90 degrees (90, 180, 270, ...) do not result in a loss of image quality, nor do horizontal and vertical flips.

Hm-m. I read that JPEGs do. And that's about 80% of the general purpose image format.

My intent was to address "images", not files. The conversions that take place when importing and exporting files into and out of GIMP may or may not cause some picture degradation; but once in GIMP, using any of the rotate* or flip comands in the "Image->Transform" and "Layer->Transform" menus does not cause a loss in image quality. For these operations, none of the pixel values are altered, only their positions change (e.g., one could perform thousands of "Transform->Rotate 90" ops without ever changing a single pixel).

* "Layer->Transform->Arbitrary Rotate..." will cause image quality loss if the angle specified is not a multiple of 90 degrees and, even if it is a multiple of 90 degrees, may cause quality loss depending upon the center's location.

I tend to agree with Saulgoode's explanation, not that this matters all that much.
As explained... the loss of image quality is highly apparent when using other then the Image>Transform to flip or rotate an image.