This technique refines the reader's perception of the poem. Just like in films, whenever the director zooms in we know that we are supposed to pay attention since important information is being presented. The speaker tells us that he is waving and the twitching; twirling of his shirt is his desperate attempts to attract attention. The word 'waving' reminds me of a poem by Stevie Smith entitled 'Not Waving But Drowning' in which a drowning man's signals for help are mistaken for waves, a cry for a help mistranslated as a reassuring gesture of goodwill. In 'Out of the Blue', this same wave forms an interesting juxtaposition between the horror of the situation and a friendly gesture of a wave. On the other hand we might also think about the implications of a wave of goodbye, one last salute to the world. The poet continues with his use of juxtaposed images with the speaker contrasting his terrible situation and his waves with that of pegging out washing and shaking off crumbs. The effect of this isn't to diminish or trivialise what is happening but to emphasise the extremity of the situation. Like many of Armitage's darker poems this also has a hint of macabre, his use of juxtaposition doesn't lessen the impact but makes it stand out as all the more terrible. If we look closer we see that the third stanza starts with a direct question to the onlooker, 'so when will you come?' which I read as a desperate plea for help, hence the comparison between shaking crumbs and fighting for life. The repetition of 'trying' and use of end-rhyme in the fourth stanza add further emphasis to this sense of impending doom and anxiety. The heat of the fires behind him are 'bullying' him towards his death, 'driving' him, although he is not yet ready to surrender. We sense his end is close.