The centre button of the row at the top of the Layer Manager is the options button. When you click on it, there is quite a long drop-down menu of options you can use with an object or objects. Some of the options, like merge and add shadow are also available on other menus, but are accessible from this one too for convenience. The last option on the list is Properties, and this is the one that interests us.

Make sure that the roses object is selected - if it is not showing the blue line around the Layer Manager thumbnail image and background to the filename, click on the thumbnail to select it. You can also select an object by clicking on the object itself in the image. If you click on the area outside the thumbnail in the Layer Manager, you will see not only the blue disappear from the thumbnail frame, but also the marquee disappear from the roses image. Click either on the roses in the image or the thumbnail in the Layer Manager, and both the blue on the thumbnail and the marquee on the image will reappear.

Once the object is selected, click on properties in the options menu and this dialogue box will appear. From here we can control an object's overall degree of transparency, which colours or range of colours are to be transparent, whether the image is to have a soft edge that blends in better with its surroundings, its position in the image window, and we can lock it in that position or allow it to be moveable, or even hide it so that it becomes invisible in the image window. The URL option allows us to make the object into an image map. But the option which concerns us in this tutorial is the one I have outlined in red - the merge or blend modes.

The arrow to the right of 'Always' gives access to a drop-down menu with a choice of 13 modes. They govern the way that an object blends with whatever is underneath it. The pixels are compared, and the colour of the pixel which is displayed is determined by applying the rules of the merge mode in use to the comparison. Always displays the object as if it is a separate image. Nothing is changed and where it overlays something underneath, whatever it is, that will be hidden. Increasing the object's transparency is the only way to reveal what is below it when in Always mode. So, since our roses completely cover the ramp, they alone are visible in this mode, and the ramp is totally hidden.

Hue and Saturation blends the images by comparing their colour and their intensity. In practice, it means that the roses 'win' when they are have more or darker colour than the ramp. When the ramp has more colour, or its colour is more dense than the roses, the ramp hides the roses. In this image, the ramp is grey and black. What happens if it is some other colour?

Here I have colourized the ramp to green shades. In fact, both elements are more obvious now in the merged picture, because the hue and saturation levels of the green are closer to those of the roses than the greyscale ones were, so they are blended more equally. I will continue show you the comparisons between merging with greyscale and merging with colour.

When we change the merge mode to hue only, and only the colour of the pixels is compared, the difference between the greyscale and green ramps is very marked. The greyscale ramp completely dominates the blend, and the roses do not show at all. With the green ramp, the pink colour shows through and the green is hidden. The ramp shape is visible, because the very dark green rings are a stronger hue than anything in the roses. The creamy colours and the lighter pinks are not often reproduced, so we have no impression of roses here, but the pink is dominant.

When the merge mode is saturation only the pixels are compared on the basis of the colour saturation alone, and the colour shade or hue does not come into it. The result with the greyscale ramp is exactly the same as for hue only. The ramp is completely dominant because its colours are more saturated than the pinks of the roses. With a green ramp the picture changes a little. Now the pink is sometimes the more saturated colour, and we can just discern the shapes of roses, albeit green ones, among the medium to light medium tone circles of the ramp. They are not coloured pink, because it is not the hue determining the dominant pixel here, but the saturation of the colour at that point. The pattern of the more saturated areas of the roses is applied to the ramp image, and the ramp image colours are used.

The luminosity only merge mode shows pretty clearly what happens in merge modes where colour is not a determining factor. In both of these images, the roses frequently have more luminosity than the ramp, so their pixel pattern is applied to the ramp image, and the ramp image colours are used. With the grey ramp, we are left with a monochrome image of roses, because there is no point at which the ramp luminosity is greater than the roses. With the green one, the pattern of the ramp is still discernible because there are points where the ramp has the more luminous pixel. The roses are a little fainter than with the grey ramp, and they still use the ramp colours, so in the centre, where the ramp is white and so there is no green shading to apply, the ramp colour is interepreted as monochrome and roses appear as greyscale.